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.
Critical Dissonance: The anime has become this after its first episode aired. The consensus among many viewers is that it isn't good due to the controversial art direction, while reviewers generally have been quite positive about the series, including the art direction.
Fan Nickname: Aku no Potato, based on the... controversial character designs and animation methods employed by the anime. Another favorite is Rotoscope no Hana
Freud Was Right: Certainly comes true in later chapters, though Nakamura gives clear indication she believes this.
Internet Backdraft: The anime adaptation was originally subject to this by the truckload due to its rotoscope animation.
Whatever you may think of him, there's no denying that Kasuga's life has become an utter hellhole thanks to Nakamura and he at least deserves some pity. That is, if it wasn't his own fault to begin with though.
Some of his problems definitely were his fault. However, it was clear that he was always very meek, insecure and impressionable, making him ripe for Nakamura's destructive influence.
The chapters leading up to the Time Skip made Saeki to be a pretty big one as well, even after she committed rape and arson in an attempt to win Kasuga over.
Nakamura. It is very clear that she is suffering from some kind of severe unnamed mental illness and is unable to cope on her own or prevent herself from dragging Kasuga down with her. Also, she very well might have strong feelings for Kasuga, but is unable to express them due to her illness.
Just Shoot Him: Pretty much what many readers of the manga are stating towards Nakamura and Kasuga.
Kasuga's reception has gotten quite a bit better after the Time Skip, especially after he Took a Level in Badass out of the blue. Even people who hated him in the past and/or still hate him admitted that pouring his heart out to Tokiwa in front of her boyfriend was a pretty ballsy move. Other people have said that him finally having something go his way made him a more relatable character.
Moral Event Horizon: Nakamura crosses this when she smashes Kasuga's father's kneecap. Before that, she had done some terrible, terrible things, but that was the moment where her acts of cruelty became irredeemable.
Narm: The anime adaptation provoked a fair amount of this reaction in some viewers due to its controversial rotoscoped style and its associated quirks, including very strange or occasionally non-existent facial expressions, actors who really didn't look like teenagers, certain directorial choices that created moments of weird pacing and other factors that made it difficult for them to treat the subject matter too seriously.
The Time Skip has drawn some complaints due to Nakamura being put on a bus as well as Kasuga starting to have an actual romance that has yet to be destroyed by either her influence or his stupidity.
Tear Jerker: The last few chapters of volume 3 have been this for all characters — yes, even Nakamura.
Saeki's "The Reason You Suck" Speech toward Kasuga is heartbreaking and oddly nauseating when you take into account that she raped him yet has the audacity to invite him to lunch... and then tell him he's a terrible person.
Uncanny Valley: The animation of the anime uses rotoscope instead of traditional anime-style which places the series pretty close to the bottom.
What an Idiot: Kasuga consistently falls into this, perhaps out of a desire for self-destruction. He always seems to do the worst possible thing at any one moment, and it always come back to bite him. To say he can't let go of the Idiot Ball is an understatement.
Kasuga's parents. They watched their son grow more and more distant only to discover the horrible acts he had committed. His mother eventually broke down and proclaimed herself to be a total failure as a parent.
Likewise, Nakamura's dad is arguably is one too. It's clear from his behavior that he's concerned and worried about Nakamura, in spite of her psychopathic behavior.
Kinoshita. She was probably the character that hated Kasuga (and Nakamura) most, but she would soon have legitimate reasons why not to like him, especially considering what happens to Saeki later in the manga. Post Time Skip reveals that she feels immense guilt over what happened to Saeki despite the fact that there was really nothing more she could do. She breaks down crying when Kasuga tells her that Saeki's off living a normal life because she feels that Saeki abandoned her. Judging from how she worded it, Saeki's not the only person to do so.