These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Chapter 113 has left very polarizing opinions. It is either seen as an extremely disappointing ending that shoehorns breasts in the first half and doesn't explain or resolve anything, or a really decent and fun ending that makes nice callbacks to the prologues of the series and ties up everything just fine. The fact that the heroes never have a rematch with Medusa who ultimately offs herself as part of making Crona the ultimate weapon didn't go over well either.
Ironically the ending of the anime likewise was a source of breaking. Some fans found the whole "Courage" can beat Asura ending rather cheesy and cliche while others thought it was a nice and simple metaphor for the series as a whole. Now that the manga has ended, most opinions on this have shifted to the latter since at least they managed to put down Asura in a more satisfying fight in the anime as opposed to neither side managing to overcome the other in the manga and Asura essentially rage quitting when he can't break the main heroes and sealing the moon.
Complete Monster: Medusa turned the show from a funny, off-kilter shonen series into an almost-Cosmic Horror Story. She's a witch who has used her own child, Crona, as a horrible science experiment, driving them to complete madness and not showing an ounce of love, much less regret. When Crona is finally shown, for the first time in their life, true kindness from Maka, they do a Heel-Face Turn. At this time, Medusa is also trying to revive the Kishin using two witches, Eruka and Mizune, that she blackmailed into helping her—she can off them with a snap of her fingers. When she's defeated by Stein, she escapes in the form of a snake and takes over the body of a little girl, knowing that the protagonists won't kill her if it means killing the child. She gets Crona in Shibusen to act as The Mole and drive Stein to (greater) madness. When her sister Arachne is revived, Medusa goes to Shibusen to ask for their aid in defeating her—she's given Shibusen's best students to help with the job. At this point, Crona's been captured and Medusa tells Maka it was Arachne who took her. When Maka defeats Arachne, Medusa takes over her sister's body and tells Maka she lied: she was the one who captured Crona. As of recent chapters, we see Medusa has driven Crona to insanity and broken him/her again to use against Shibusen and anyone else who stands in her way, all just as an experiment. She then gives Crona the first hug she/he ever got from her, driving her completely mad and killing her, all part of her sick plan.
Too many examples to list. Suffice it to say that if you go three episodes without seeing something that qualifies, you aren't watching Soul Eater.
Black Star certainly qualifies. He constantly straddles the line between this and Too Dumb to Live. Slams squarely into the former, however, during the Rescue Kid arc. G.O.O.'s attempt to make him crazy just makes him more awesome and shakes the insanity off through a mix of being too proud and too stupid.
Stein is a frankenstein-y doctor those tendency for insanity makes him feared by both sides.
Kishin Asura is a monster whose insanity can cause hallucinations by his presence.
The sheer menace of Justin's fully transformed self as a living guillotine makes it very clear as to why he didn't need a wielder to obtain Death Scythe status. Up until that point, he's simply been content with Blade Below the Shoulder, but when he fully transforms, he's got what are basically meat cleavers on the ends of Variable Length Chains, stocks to trap and sever the necks of anyone caught in them, and a seriously creepy Slasher Smile.
Die for Our Ship: Marie gets this treatment a lot by Stein/Medusa and Stein/Spirit shippers, even though her relationship with Stein doesn't seem to be going anywhere beyond Ship Tease. By the end of the series, she's carrying Stein's child. Not that the shipping ever goes away, but there's at least one happy faction reveling in Canon.
Soul/Maka fans are scary, some fans have even reported being harassed at conventions for the "crime" of not shipping it.
Ear Worm: "Excalibuuur...Excalibuuur...from the United Kingdom...I'm looking for her...I'm going to Californiaaaa...".
Also applies to FUNimation. He's the favorite of numerous cast members, and the role was given to Troy Baker, who is ActionBastard!... on a show that has the same ADR director!
Death the Kid is one, sharing the top spot with Stein as the most popular character in the series.
Soul's older brother, Wes, is fairly popular, particularly with fanfiction writers. This is surprising given that every scene he appears in is either a flashback, or an illusion, that Soul is having. He never makes a proper appearance in series, and so what little we know of him comes from Soul's, most likely, skewed perception. But even so, he is more than often used in several fanworks.
Probably the only kishin that can be classified as this is Asura, if not only for that behind his mask, he is actually quite the Bishōnen. Too bad he rarely ever has his mask off. His introductory scene of him putting his skin back on didn't help either.
While the Meister/Weapon pairings undoubtedly have their fans, there is quite the sizeable fandom for Kid/Crona... it doesn't help that it would probably come just behind Stein/Marie in the Hurt/Comfort department.
Don't forget Maka/Crona.
And Soul/Maka. To the point where Maka/Crona vs Maka/Soul could be a Base Breaker. Both have several points of canon and rabid fans.
Franken Stein and Medusa. Opposite sides, yet clearly attracted to each other; both appreciate the appeal of insanity and taking rules (and people) apart.
Justin and Giriko could also count since the anime portrays them as rivals.
Genius Bonus: For Death the Kid to talk to his father whilst in the field, he casts a spell by doing a couple of hand signs. The last sign◊ he does is American sign language for 'I love you'.
Having Justin be a very religious guillotine in charge of the DWMA's European branch might be a reference to a litany from the French revolution about "Saint Guillotine". Also in a case of foreshadowing or averting Artistic License - Traditional Christianity, the upside-down cross is a very prevalent symbol on Justin's sleeves and his fully powered soul's guillotine which could account for either since while it is a Christian symbol used to show humility or as a tribute to St Peter it is often mistaken as a Satanic symbol.
Which makes for an odd comparison with Spirit. They are both loyal to the 'god' they serve. It just so happens that they're not serving the same being.
Germans Love David Hasselhoff: In Italy, apparently it was so popular among the scanlations-reading fans and such that the manga was translated and published because of it, and was quite popular for a long time. The fact that the anime was translated and aired uncensored (it's one of the few Italian dubs to include Precision F-Strike here and there) probably helped.
Crona's a boy! Crona's a girl! CRONA'S A BOY! CRONA'S A GIRL! BOY! GIRL!!! BOY!!! GIRL!!!! BOYGIRLBOYGIRLBOYGIRLBOYGIRLBOYGIRLBOYGIRLAAAAAAAAAAAAAARGH! *tears hair out*
At the end of October 2009, FUNimation's reveal of the English voice for Black☆Star on YouTube garnered near-500 comments in 8 hours of people arguing about how bad her voice was! Way to go, FUNimation. 'Bet they'll think twice about posting previews of their voices online from now on. (Poor Brittney Karbowski, tho.)
Jerk Sue: Black☆Star. Although he's a jerk throughout, he has Jerk with a Heart of Gold moments towards the beginning that make up for it. As the anime progresses though, he continually does dumb things, but anyone that tries to point them out either gets called out for being a jerk to Black Star, or they change their mind. The two worst cases would be episodes 33 and 38: in the former, Black Star's arrogance throws off the Chain Resonance, something stated directly by Stein himself, but Maka is called the problem when she tries to call Black Star on it; in the latter, Black Star blows off everyone, acts like more of a jerk than normal, and challenges Kid to a duel just so he can prove his power to himself after failing so many times... and Sid and Tsubaki let him off when Maka tries to stop it, saying it's just the way he is and they have to accept that.
In the first opening, at one point Blair is seen jumping on a table in Maka and Soul's apartment with the whole gang over. Maka is disgusted/annoyed. Tsubaki doesn't seem to know what to think. Death the Kid and Black☆Star freak out, Soul gets a nosebleed. Patty and Liz, who were right near Blair, appear to be pleased with what they see.
Jacqueline and Kim, though it seems more from Jackie than Kim.
Also Tsubaki and Maka as implied in Chapter 90.
Like You Would Really Do It: Chapter 112 ends with Spirit, Marie, Sid, etc trapped on the Moon thanks to Crona sealing away the Kishin, basically meaning they would have been killed off. Come Chapter 113 and it turns out Mabaa used her spatial magic to save them.
LGBT Fanbase: Free, probably due to being hairy and muscular.
Medusa, the Knight of Cerebus in the series, she exploited the usual Dark Magical GirlHeel-Face Turn by turning Crona into The Mole, succeeded in awakening the Kishin, only "lost" to Stein and Death Scythe because she won, took over the body of a small child so no one could attack her without hurting the little girl, drove Stein to madness (the not funny kind), outed a good witch who just wanted to defect, and is leading Shibusen against her rival with Shinigami-sama's blessing.
And her Magnificent Bastard Quota keeps rising exponentially! Turns out, the whole reason behind leading Shibusen to defeat Arachne was so Medusa could steal her sister's gorgon body when she abandoned it to become madness incarnate, and to try and kill Maka, who's Demon Hunter wavelength apparently poses a threat to her and the entire witch world. Also, as of the new chapters, she is manufacturing FAKE MADNESS CLOWNS from information she got from Shinigami and Arachne. [[spoiler: She got Crona to kill her. But what should be a Crowning Moment of Awesome for poor Crona... became a HELL of a Thanatos Gambit for Medusa. Wooooooooooow.
Excalibur is an odd meta example. On one hand, he's universally despised in-universe but has a large number of fans in Real Life. Then there are people in Real Life that have the same 'just met excalibur face' as the characters.
Ships That Pass In The Night: Kid/Crona quickly became one of the most popular pairings in the fandom despite the fact that the two of them rarely, if ever, interact.
Somewhat Hilarious In Hindsight considering the end of the manga refers to the similarities in their upbringing and (intended) destinies, precisely the sort of thing shippers take as fanfic fodder. They are, in a technical sense, closer parallels than Crona and Maka.
They Wasted a Perfectly Good Character: Blair is absent for many of the major story arcs and her backstory is mever given much details besides "a cat with magical powers." Tsubaki also gets only a couple of chapters to flesh out her character and then is basically resigned to a role as 'Black*Star's Weapon', reacting mainly to whatever is happening to him.
Poor Tezca Tlipoca... and he had to die more than once!
Mifune, Mosquito and Joe Buttaki.
For the villains Medusa as well
Villain Sue: To people who don't gush over Medusa's Magnificent Bastard status, she is this, always having a plan ensuring her victory and having extreme luck in some situation, like her constant avoiding death.
In the Manga Even in death she still got what she wanted. That is, until Crona finally decides to 'deal with' hir fear. Granted Asura is still a threat - in that a personification of 'fear' cannot truly be destroyed - but that's not down to Medusa's actions.
What Do You Mean, It's Not Symbolic?: Among other things, Crona's name is a play on "Kuro na", translating as "dark one". And just for a moment, Lord Death and Asura's competing auras form a yin-yang symbol.
Crona might just be the woobiest woobie that ever woobed.
They may be the biggest one, but they're far from the only one. We have Maka with her massive insecurities, Soul with his inferiority complex (manga only), Tsubaki with her brutal sibling problem, Liz and Patti with their Dark and Troubled Past, Stein with his constant struggle to keep sane, Eruka with her forced servitude to Medusa under threat of death, heck, even Ragnarok could qualify (see Fridge Horror above).