Anti-Climax: After nearly 700 pages of build-up, XXI appears on screen for the first time. And then, the chapter ends with a bad gag before heading into a special.
Ass Pull: Future Gohan's victory in the "Mirai" special is only made possible by a series of complete and utter asspulls. First, Gohan somehow manages to avoid being killed by Dabura by showing far superior speed and reflexes to characters that are canonically way faster than him, including Buu Saga Piccolo and the main timeline Gohan. Oh, and he also somehow survives a punch from Dabura, when it's repeatedly shown that if a fighter that strong even light taps someone that weak, they can make said someone EXPLODE. Then he gets teleported onto another planet with Yakon, a monster who can easily kill him via energy drain. Coincidentally, just Yakon is about to drain Gohan, Yakon's sister, a new character who was never even implied to exist in the source material, shows up and starts screwing around, keeping Yakon distracted long enough for Gohan to to start blasting holes in the ground and making vague threats at Babidi. Then, for no reason at all, Babidi transports Gohan back to Earth rather than leave him to rot in nowhere space. Oh, and he doesn't bring Yakon back for some reason. However, Dabura's still there, so Gohan still has no chance, right? Well no, because then the crowning moment of ass-pullery occurs: Babidi drains Dabura of the vast majority of his power right before telling him to face Gohan. We're talking a huge drain, over 95% of the guy's power. Why? Because he almost killed Gohan, keeping Babidi from getting energy. For some reason it never occurs to Babidi to "punish" his mind controlled slave AFTER Gohan is dealt with. Or just to take less energy. Finally, due to this awfully convenient turn of events, Future Gohan is able to beat a guy dozens of times stronger than him and save the day.
Chapter 29 Special has been praised for having a better art than the rest of the special chapters. It was drawn by a new artist on the team, and has made this special probably the best received so far. Here it is.
Chapter 41 takes on a very different, more realistic style. Despite being another filler chapter, nobody really minds, because the art is both amazing and visually distinct, and Gast is a walking collection of awesome.
Pan: She is a fun case. Her haters are usually people who despised her Dragon Ball GT counterpart, and transfer that hate to the DBM Pan. Ironically the two characters are drastically different, with Multiverse Pan lacking many of the complaints of GT Pan such as her brattiness and is truer to her Z personality. Her supporters are quick to point this out and like how her character arc involved her accepting her role as one of Earth's protectors and transforming into a Super Saiyan.
XXI: He was a very anticipated character that fans universally wanted to see. Once he actually appeared a small number of people were a bit disappointed. After his match against Vegetto he split the fandom. There was a surprising number of fans who agreed with Vegetto and U4 Buu that XXI cheated. They reasoned that XXI's technique transported Vegetto into a dimension where time runs much slower than the outside world let him win by default thanks to the 30 count. They feel he abused a technicality, and violated the spirit of the tournament format. They wanted a rematch between Vegetto and XXI as much as Vegetto and Buu did. There are people who felt XXI's move was legal and that it was a good strategy. This belief is shared by U16 Gohan. He pointed out had the match been a real fight the technique would have still allowed XXI to achieve his objective before Vegetto could even break out of it. His victory over #18 by using the remote deactivator has split fans even more. One camp enjoys that he's using tactics and wits to outsmart his foes. The other feels it ruins the spirit of Dragon Ball, which favored straight-forward combat.
Son Bra of U16: Some people think she's one of the best characters in the setting, others regard her as an overpowered Mary Sue and an arrogant Jerkass who has no respect for anyone other than her father and a handful of others. And even they are often on the receiving end of her normally very crude insults.
King Cold's augmentation forms created an unprecedented number of comments, both positive and negative. Some think they look awesome, others think the awe factor is outweighed by how stupid they look. Some say that it makes total sense for Cold to have two augmentation forms, while others point out that the augmentation forms were supposed to have only been discovered by Cold, and question how he could have found two. Worse, they managed to stir up arguments about Son Bra.
Big Lipped Alligator Moment: The beginning of the tournament's second day is celebrated with a musical performance by the Star WarsCantina Band. Pan and Tapion enjoy the musical interlude, Bra, Frieza's Family and Babidi do not. Zen Buu thought it was so bad that he demanded that they give their instruments to him so he could play.
The specials. Are they good side stories to have while the main tournament fights are being drawn and helps flush out characters we had no screen time, or are they a waste of time and most prefer to wait longer from a chapter instead of reading the specials. Another group like the idea behind the specials, but think they're being wasted with the villain win stories, instead of more interesting stories like how did Cell beat Buu in the universe where he won, or how he dealt with Bojack.
The art in the specials. Some like that different artists do them in their own unique style instead of trying to copy Toriyama's artwork, while others dislike it since the quality widely varies.
The overall length of the series. There is a group of fans who believe that the comic has gone on too long and have lost a lot of its luster, especially since it can't incorporate material from Battle of Gods, Resurrection 'F', and Super since it doesn't fit within the story of Multiverse. Others think the length is fine and Multiverse is better off not including material from the The New Tens.
Canon Defilement: The series violates all levels of the canon at various points.
Salagir openly admits that he ignores the guidebooks and substitutes his own fan theories for them, even though they're official material and approved by Akira Toriyama himself.
In the manga, King Cold repeatedly states that Frieza is stronger than him, and that anyone stronger than Frieza would automatically be seen as the strongest in the universe (excluding Cooler of course, as he's anime only). In DBM, Salagir ignored this and gave Cold two massively powerful forms he was never stated to have. This has been a long point of contention for fans of the original series, since Frieza stated his final form was his original one it would logically follow his father would resemble said final form, unless he was himself transformed. Frieza and Cooler's reactions in-comic suggest that Cold had the same problem as Frieza when it came to controlling himself in his original form only worse, enough so that he almost never bothers to transform. The fans who accepted these new forms were less than impressed when Cold revealed two forms even more powerful than his "true form". Particularly notable since, not only did these not exist in canon, they conflict with a prior comic which stated that Cooler was the only frost demon with such augmented forms.
According to the guidebooks, only Namekians of the same clan can fuse. The only reason why Piccolo and Kami are able to fuse despite Piccolo being a Warrior-type and Kami being part of the Dragon Clan is because they were originally the same person In DBM, this restriction is lifted, making the existence of Gast Carcolh possible.
In the manga, Babidi couldn't drain his own minions for use in the resurrection of Buu. He states that only "good" (morally) energy can be used for Buu's resurrection, and all of his minions are evil. If he could, he would've just drained Dabura over and over until the meter filled. In DBM, not only can Babidi do that, but he uses it as a PUNISHMENT, draining Dabura of nearly all of his power before sending him off to fight Future Gohan. The author admitted that he did this because even he couldn't see a plausible way for Gohan not to get killed in one hit.
Salagir is also very open about the fact that he "allows himself" to change non-manga materials as he pleases, i.e. the movies (not that he stays true to the manga either). In particular, almost everything about Broly, from his power to the story of his second movie, because Salagir thinks he's cool.
It's stated in Multiverse that Super Saiyan 3 drains a user's power more quickly the stronger they are, especially if they get older with age. There is nothing in canon to suggest this. In fact if GT Goku is any indication, an adult body handles the strain better than a child body.
Creator's Pet: Universe 20 Broly. Salagir exaggerates Broly's power, moving him from "extremely powerful" to "invincible" while in his Legendary Super Saiyan state. Additionally, he gets a lot of focus despite being an ultimately unimportant character (his fight with Vegito being the Batman Cold Open of the entire series). This occurs because he thinks Broly's awesome. Broly is pretty unpopular with the hardcore Dragon Ball fanbase due to overexposure, so this blatant favoritism doesn't go unnoticed.
Frieza Butt Monkey status is particularly hilarious given the Dragon Ball Z: Resurrection ‘F’ movie where he's Post-Battle of Gods Goku's level. As in, Resurrection 'F' Frieza would mop the floor with the entire tournament.
During the tournament, Goku is stun when he feels Bra's power as a Super Saiyan, proclaiming her stronger than Vegeta and him. With Battle of Gods, Resurrection 'F', and Dragon Ball Super, this line comes out as unintentionally funny since Goku and Vegeta's base forms are stronger than Super Saiyan 3 Gotenks.
In Multiverse, Goku's mom is a hardcore Saiyan warrior who was the strongest Saiyan alive. Goku's canon mother is the exact opposite, being a soft-hearted person who wasn't cut off for battle.
Years after being a fan premise, Dragon Ball Super is making a "inter-universal battle" a reality. It's made even funnier when, just like Multiverse, the main universe in Dragon Ball averts The Earth Prime Theory. Even more hilarious, Zen-O, the King of Multiverse, wants to hold his own tournament with all 12 universes instead of just U6 and U7. Champa calls his tournament the warm-up with Zen-O's tournament being the main event.
In a more specific example, both stories have an alternate universe where we see what the Saiyans would be if Frieza hadn't existed. Multiverse's Universe 10 shows them as barely better than cavemen and so ridiculously weak that even turning into Great Apes can't help them, while Super's 6th Universe shows them as becoming a race of noble heroes who have evolved beyond the need for tails, and one member is powerful enough to impress his universe's God of Destruction. Cabba, the Saiyan from U6, is strong enough to fight evenly against Vegeta in his base form, after he has been training with Whis. For reference, in Super, base form Vegeta is stronger than Super Saiyan 3 Gotenks to the point that he can no sells hits from him and takes Gotenks down in a couple of hits.
Karma Houdini: This is one of the major accusations leveled at Bra from U16. Her detractors claim that, so far, she's been acting like an utter Jerkass, treating anyone weaker than her with derision and has yet to receive any comeuppance for her actions.
U13 Kakarotto...just see this page◊ and Chapter 27... Made even more horrifying by the single fact that, had the Goku we know and love not hit his head as a child when his ship landed on earth, that's what Goku would be today... Oh, it gets worse. Turns out Kakarotto and Krillin were good friends, and for one panel, we see Kakarotto being as innocent as his U18 counterpart.
The Kaioshin's rather direct way of dealing with upcoming dangers, like killing Frieza and Cooler when they were children and Broly when he was an infant, in the Universe 1/10 Special was noted to be too violent by fans.
To many, Pan, who was redesigned from her counter part, being given more similarity to child Goku.
Uub may also qualify. While it's true that he had a supporting role in GT, he quickly became unimportant and something of a small fry. In DB:M he at least gets to show off a bit.
While chapter 14, 16 and especially 18 have been panned by pretty much everyone (as you can see below), the next special, despite being even longer than all of them, as it lasted for two chapters, was received well enough for most readers to be again interested in them. The Universe 7 special was well received as well.
Rooting for the Empire: As a result of many of the villains being much more likeable and charismatic than they were in the main timeline, and Vegito and Bra being far less likeable while receiving greater focus, it's not uncommon to see people cheering for the villains.
Frieza gets the short end of the stick in EVERY universe he appears in. The one version of Frieza taking part in the tournament has had no increase in power, when he could have had a 5th form or some other kind of interesting transformation.
The U19 Tech Warriors are the most unique fighters present in the whole tournament. Thus far, they have either been casually beaten in battle, or in the case of Eleim he only won by a tiny margin. And now they've been knocked out of the tournament entirely after having the faintest hints of their backstory explored. Thankfully this is finally starting to get subverted. U19 is getting its story told in novel/fan fiction form that is on the DBM site.
If you ask any fan of the comic most of them will say a lot of characters are being wasted. Uub probably qualifies. Like his GT counterpart his role in the overall plot has been small. This might be because he's only had one match so far. A small, but vocal part of fandom don't like that Goten and Trunks of universes 16 and 18 are just as childish as they were as kids and feel Salagiri wasted two promising characters by reducing them to joke characters who are even shallower than their canon counterparts. The girls from U6 have been getting complaints. Fans feel they are unnecessary since their backstory hasn't been explored yet nor have their characters made any impact on the tournament besides being fodder for stronger characters. Many felt U6 special should have told the girls story instead of showing Bojack and his gang kill the Z-fighters.
Some longtime Dragon Balls fans think the entire webcomic became wasted the longer it went on. Instead of writing more Ultimate Showdown of Ultimate DestinyWhat If? fights like Cell vs. Dabura and Nail vs. Recoom, it shifted to using more and more OCs in the plot and tournament.
Fans love the concept of multiverse with various universes, different from the main DB universe, but some feel its being wasted for a tournament. Many fans feel the specials as a whole are wasted because most of them retell how canon events went except with the villains winning instead of exploring the repercussions of the villains' victories. The U6 special got a lot of complaints because it showed Bojack and his minions killing all the Z-fighters and never even showed the girls in U6 at all.
The U17 Special was disliked for similar reasons. What, Cell killed the Z fighters in his universe? Naw, ya think? Plenty of fans were wondering why they didn't show, say, how Cell dealt with Babidi.
The Future Majin Attack special in a way. The special was better received the most of the other ones, but there was still out cry from fans on how forced the plot was to make Future Gohan win against Babidi and Dabura. See the Ass Pull section for more details. Instead the special could have been centered around Future/U12 Trunks and 16 and how they dealt with Babidi and Dabura coming to Earth to revive Majin Buu.
A recent minicomic revealed that U8 Paragas and Broly are still around, but chose to live in peace instead of attacking Freeza and his PTO, who are still dominant in the universe. What would have been an awesome special in itself, it has been decided it is not worth exploring, let alone other universes where multiple evil factions would still be around.
Vocal Minority: Among DBM fans, there are a few "regulars" who post more or less every page.
The Vargas who decided not to bother sending Broly back to his universe after the Broly vs. Vegetto fight.
Dumbass Has a Point: As far as they knew Broly wasn't a threat anymore and in the long run it would be safer to leave him in the lifeless universe the tournament is taking place in rather than send him back to his populated home one.
The Grand Supreme Kai being willing to let U4 Buu compete after his rampage was a relief to fans who felt it was too soon for him to exit the story, but the fact is that he allowed him to still compete is still foolish. It is true they have him contained at the moment the fact of the manner is that since he learned how to overcome Vargas technology and manipulate it means he is resourceful enough that him over coming the technique used to contain him is not out the realms of possibilities. U16 Gohan already told the Kais everything about him, meaning that the Grand Supreme Kai already knows just how dangerous he can be. However, as of Chapter 42, East Supreme Kai seems to think that he is actually being controlled by him.
Universe 8 Gohan is commonly seen this way after it didn't even occur to him to use the dragon radar to search Frieza's ship, frantically checking every room instead.