Angst? What Angst?: Despite having been locked in a room with no one but a Djinn for most of his childhood, Aladdin shows very little signs of mental strain over this outside of flashbacks. Chapter 237 reveals that Aladdin actually had angst over it, to the point of having a Freak Out!. It was Ugo being his friend rather than his servant what allowed him to see his confinement as enjoyable. Fanon likes to think that Aladdin actually has claustrophobia.
The fight against the Medium throughout the climax of the Magnostadt Arc ended up as this trope. Several Padding skirmishes against the Medium, which amounted to nothing more than the continued use of the Worf Barrage, takes place so that over time, more and more of the manga's major characters enter the scene up until the point where literally every named character introduced the past 200 chapters is on the scene. Ironically, the Medium is defeated just moments after the last primary characters, Judar and Hakuryuu, appear.
The final arc has been receiving this reaction from many readers. From David and Sinbad fighting over who gets to be supreme god, to the sheer escalation of the stakes at hand, there's a lot of criticism to be had for it, especially since the final arc lasted for more than two years.
Base-Breaking Character: Arba/ Ren Gyokuen has really divided the base considering her development at the end of the Alma Toran arc. Some of the fans think that her sudden change from Solomon's most devoted follower besides Sheba to a zealot nihilist that wants to destroy the fate Solomon sacrificed himself for comes out of nowhere. Her murder of Sheba is ruthless and without hesitation, which seems strange considering how earlier chapters had built up their relationship. Some fans attribute that these sudden changes were due to the author being rushed to finish the Alma Toran Arc.
Those who felt the conclusion as anti-climatic had their hopes up with the reveal that Arba's mind did not fully go away and found a new vessel through Hakuei. So the Anti-Climatic reactions are now averted.
The same reaction is evoked towards Hakuryuu pulling a Heel–Face Turn, since while many are pleased that he has finally found peace with himself, many others have also seen this as rushed and forced. The latter half believe that him turning away from depravity had happened too suddenly and too easily, thus it had overall cheapened the development his character had undergone for the past forty chapters.
They believe it also wasted the chance of him being an excellent Foil to the main characters to demonstrate that one who falls into depravity is not automatically evil, and that not everyone's personal conflicts can be remedied with the usual shounenmangaelements so easily.
In the conclusion of Chapter 282, fans find their hopes up with the reveal of Arba possessing Hakuei above, but some finds this rather rushed, especially with some fans hearing that the new chief editor of the Manga magazine Ohtaka works for is rushing the older Mangaka's to finish their works to give more chances for newer ones to show their work.
King David Jehoahz Abraham is the King of Alma Torran of the past and the ruler of the Magicians. As King, David oppresses all non-human species in his empire with magic towers constructed to steal their reason and intellect, turning them into feral, mindless beasts under the control of the human ruling class. Having discovered the form of "Ill Ilah," an Eldritch Abomination known as God, David makes plans to surpass it and take a seat as God himself. When his son Solomon rebels against David's tyranny, David bides his time until Solomon and his True Companions attack David's capital. David lets them attack a decoy, before leading his magicians in his own entourage to butcher the helpless civilians, including the children. The young son of two of Solomon's closest followers is found hideously burnt and dying, but still alive, begging his mother to save him as he dies in her arms. The one fighter who attempts to stop David is mercilessly slaughtered with nothing short of cold satisfaction. When engaging Solomon, David shows no regret or remorse, proclaiming his grand ambitions and utter megalomania.
Arba, once one of King Solomon's most beloved followers, fell into depravity when Solomon's will supplanted that of Ill Ilah's. Devoting herself to destroying the kingdom of Alma Torran, Arba founded Al-Thamen, also known as "The Organization", and led an attack on the kingdom, culminating in her personally cutting down her surrogate sister, Solomon's pregnant lover Queen Sheba. Vowing to return to destroy the world Solomon creates anew, Arba manifests in Solomon's new world in the Kou Empire, having children for the purpose of possessing them when her current body is worn out. When she possesses her descendant Gyokuen, Arba murders Gyokuen's husband, Emperor Hakutoku, and his elder two sons, mocking her remaining son Hakuryu, the only son Arba herself gave birth to, for his helplessness in learning the truth. Murdering her second husband to seize the throne, Arba attempts to summon Ill Ilah back into the world to drain it dry of magic and leave it a barren, lifeless husk, devoted only to the will of Ill Ilah and to the destruction of all Solomon has made.
Creator's Pet: Not so much for the early and mid stages, but some fans definitely felt that Sinbad was headed towards this trope by the endgame. Because of his manipulations, his strength, and his late game connections and ascension to godhood, he's become one of the single most important characters in the franchise with not a lot slowing him down or putting him in his place. The time when he is made a slave for Aum Maudura in Adventures of Sinbad is largely liked because of this.
Deus Angst Machina: In the manga, Alibaba is not hostile towards either Kougyoku or Hakuryuu. This was apparently not good enough for the anime writers, who have him spend the entire Zagan Dungeon dealing with his hatred and loathing. The rearranged the entire arc for it, too.
Poor Ren Kougyoku gets lots of shit for her crush on Sinbad. Not to mention the amount of backlash she receives from Morgiana/Alibaba shippers, due to what looks to be a slow-budding romance between Kougyoku and Alibaba.
Similar to what's mentioned in Ship-to-Ship Combat below; fans prefer to kill off either Alibaba or Hakuryuu, so that their romance with Morgiana is free from any competition.
It was only for one chapter... but Toto got hit with this hard in Chapter 199 when it looked like she had become Alibaba's girlfriend off-panel. Chapter 200 confirmed that it was just the author trolling the fans.
Sinbad for various reasons. He doesn't get his own spin-off for nothing.
Morgiana. Let's face it, especially with the anime, the first thing a newcomer hears about is the Moeslave girl. And while she's certainly a main protagonist, she wasn't at first and she suffers from a lot of Out of Focus.
In addition, all eight of Sinbad's generals get love, especially for their quirks and mentorrolestowards the main protagonists.
David (Solomon's father) from Alma Torran gets to be this at least with certain parts of the fandom, due to being a Magnificent Bastard that seems to always know what will happen. Even hundreds of years in the future.
Among the characters coming from Reim, everyone seems to be particularly fond of Muu Alexius as well. Like Hakuei, it seems being a perfectly decent, friendly and charming invidual as well as a Dungeon Conqueror does wonders for the fan. And it really doesn’t hurt that he’s a very, very pretty man.
Epileptic Trees: Quite a big one popped up at the start of the Alma Torran flashback arc for who might turn out to be Gyokuen. At the beginning, Sheba seemed to be the most likely suspect since she wielded the same staff and had a strong bolg based magic, as well as being something of a religious fanatic. But as Arba started to get more focus, people began to notice that she looked almost identical (sans the Beauty Mark) to Gyokuen, as well as having a more aggressive personality. Then there were Arba's actions in Chapter 228. Only time will tell if anyone is right.
And the winner is Arba - the staff she wields is the very one that she took from Sheba after killing her.
Estrogen Brigade: The author is female, and has included a full compliment of Bishonen and Ho Yay. As a result, the readership for Magi has a pretty even male/female ratio.
The vast majority of fans seem to ship Alibaba/Morgiana due to their main-character status, and having lots of screen-time playing off one another.
Those who aren't on the Alibaba/Morgiana bandwagon would rather pair Morgiana off with Hakuryuu as a means for her to play off as Hakuryuu's Morality Pet, so that he doesn't destroy himself out of Revenge.
A third, much smaller, camp would ship Alibaba off with Kougyoku due to a slowly developing friendship/romance between the two... and as a means to get Kougyoku away from Sinbad.
Now that Alibaba/Morigana has became official, the next chapter waste no time giving us some Kougyoku and Aladdin tension, Alibaba is replaced by Aladdin to fill in the void.
Judar and Hakuryuu has been rapidly gaining traction since Chapter 242, with every chapter featuring interactions between the two of them attracting more and more fans.
Foe Yay: Judar has mentioned many times that he wants to "own" Sinbad.
He's Just Hiding!: The number of people who believe that we've seen the last of Gyokuen, after her and Hakuryuu's fight, is small both in the fandom and in-universe. True enough, Arba/Gyokuen's consciousness has found a new host: Hakuei.
For that matter, Sinbad. So far, he's been paired with the four protagonists, all his generals, the princes and princesses of the Kou Empire, the other Magi (Judar, Scheherazade and Yunan), himself....
Ithnan, who spends a good long while living inside Hakuryuu's body, then emerges completely naked to compliment him on how comfortable it was.
Kouen, who develops a (temporary) obsession with Aladdin, a little kid. During the Magnostadt war, when Aladdin promises to tell him everything about Alma Torran, he becomes determined to kill anything after that gets in his way of talking with Aladdin in private. (This is even noted by Kouha, to Aladdin's dismay). Not to mention Kouen attempting to kidnap Aladdin and take him back home with him post-war, alongside the creepy eyes and smiles he gives Aladdin whilst this is all going on.
Sinbad, who is believed to be this in-universe by his Eight Generals - as seen how they instantly assume the worst when Kougyoku accuses him of having deflowered her. Though given that he apparently groped Yamuraiha, his own subjects, and even an elderly women, you can't blame them.
One look at Aladdin and this will definitely come to mind. He's young, cute, naive... Word of Goddess is that Aladdin was originally going to be female. The Sarashi he still wears is a remnant of the early character designs.
Moral Event Horizon: Ahbmad. He endangers his nation economically, doesn't consider people from the slums to be worth anything at all, including his own half-brother, and is more than willing to sell his subjects into slavery if it means getting more money from the Kou Empire.
Sinbad might have crossed this when he showed Alibaba how far he would go to protect Sindria. He is using his Djinn to make three people unknowingly spy on their countries for him, one of which is his own citizens. Another is Kougyoku, which if he had used anybody else might have not been so bad.
And he definitely crossed it after the timeskip, only this time he mindrapes and brainwashes the entire world (sans the magi) into joining him and his scheme of eternal world peace, essentially trampling on the concept of free will all together in doing so. All this without so much of an inch of hesitation or regret from his part.
Arbadived off the slope and into the event horizon head-first when she killed Sheba and rebelled against Solomon for "killing" Ill Ilah. There is a reason this person is Gyokuen.
Same as above, Hakuryuu and Judar both cross it when they enter Belial's dungeon. Belial tries to save them and let them extinguish their inner demons, but instead they embrace them in horrible ways. Hakuryuu kills illusions, good illusions, of both Hakuei and Morgiana as well as promising to kill them for real. Judar kills a good illusion of Aladdin while telling him how easy and nice it would be to accept his friendship. As they fall into depravity, they both declare their intent to destroy the world and remake it into their version of utopia.
Narm: The Laem Empire looks like a thin anagram for "lame", and many readers are going to pronounce it that way.
It seems the Fansubs have noticed it and start to use the alternative name "Reim" which, if you think about it, makes more sense considering it's based on the Roman Empire.
Subverted! Ren Gyokuen is revealed to really be Arba, who didn't show her true colors until Solomon decided to become the new god of Alma Torran. The Magi with the Empty Eyes close to Solomon was actually the good one, Sheba.
Romantic Plot Tumor: The Alma Torran arc focuses a lot on the relationship between Solomon and Sheba. Some even have a hard time remembering that the story is not about them. This is kind of justified because out of their relationship, our actual protagonist Aladdin came to be. Although they are a popular ship and many fans love their relationship, some fans wished that Ohtaka had put more emphasis on the background of the Djinns and the different species, instead of focusing so much on just their love story and the magicians; especially since at the end it took away so much time that the really important parts of the flashback - such as the betrayal of Solomon's allies, the formation of Al-Thamen, and the final battle were extremely rushed.
Rooting for the Empire: During Reim invasion of Magnostadt, its not hard to find oneself rooting for Reim, considering the openly racistpolicies of the Chancellor, and how their weapons of mass destruction are fueled by sucking life out of the Goi.
For Solomon there is a fight over whether it should be Sheba or Arba that he ends up with, and then there are those that like the Threesome Subtext and ship all three.
Squick: Many a foreign fan are grossed out at the idea of shipping Aladdin with Judar, or anyone older due to the age differences between Aladdin and said character which made the ship seem Pedophilic.
The odd part is that despite how much the manga content changed here, it still ends up following the manga again when the second season started; one of the few rare occurrences where the anime adaptation fixes itself... though this reaction for going the anime-original route in this portion of the manga still lingers somewhat.
They Wasted a Perfectly Good Character: Some fans viewed Kouen's death as this. Many see's him as a good Foil to Sinbad and wished to see a fight between these two foils. But they never got the fight and Kouen is just executed.
Subverted big time. It turns out that Aladdin used water magic to fake Kouen's death. So those who wanted to see Kouen have an actual fight with Sinbad can rejoice.
SINBAD. Hyped as the most important man in the world and savior of humanity, he tries to reach the sacred palace and is effortlessly killed by Ugo despite his best efforts. Turns out was he was just a pawn to David, who was manipulating him the entire time in order to get close to the palace and usurp Ugo.
Subverted. Not only did Sinbad manage to come back from the great flow of Rukh, he made David/Ill-Iliah his magi and eternal servant while usurping Ugo himself and took the throne of Top God within the palace in the span of a few chapters, essentially nullifying his defeat and "wasted potential" at the same time.
Ill-Ilah. Started off as a magnificently terrifying and powerful Big Bad of the series, only to be reduced to a Cosmic Plaything by both David and Sinbad in its later appearances.
Kouha suffers from this too. His feminine hairstyle and pinkish hair don't help much.
Villain Decay: Ill Ilah got hit by this, hard after its first apperance. Its first impression as a terrifying world-devouring Eldritch Abomination which required a combined joint-effort of every single djinn-equipped character to keep out from entering their universe when summoned, made the impression of it being the final Big Bad of the series, only to be, later on, hijacked by David, abandoned by its sole supporter Arba, taken advantage of by Sinbad, crushed like an ant at the Royal Palace and then, to put the cherry on the top of its humiliation, placed in a aquarium like a pet-jellyfish by Ugo. It´s safe to say that Ill-Ilah will never be seen as anything but a joke by the fandom after that at this point.
World Of Woobie: Being a series in which bad things happen to good people, there are a lot of examples. Sahbmad is a straight up example of a Woobie.