My guess is that people got so brain f*cked and gone mad and that is why this has very low score.
you getting fucked in your brain doesnt mean that the show is bad.
story: they give you the background of the characters in backwards, you learn every thing about the characters after you finish the last episode. the story and the events will never get you bored or get you out of the unease and the painful mental state it is like a mix of emotions, the closest thing that I can think of is that it is like watching citrus and future dairy at the same time.
you have to take a break after you finish the show before you judge it, if i would to rate it in the middle of watching it i would give 1/10 for how much i suffered watching this fucked up show.
story 10/10 because it did its job as a psychological horror of fucking my brain.
art: the only "issue" is that the art is not *perfectly* matched with the story, if it was less colorful and more like (shiki, another, monster, jigoku shojo)'s art it would be a perfect complete masterpiece. the animation is amazing
art 8/10 it is still wonderful but could be a little more better.
sound: didnt really notice the sound effects or the music, it was not that memorable but it definitely got me into the atmosphere, it is good i guess .
sound 8/10
the characters : they are the best thing about the show very memorable and unique characters with each one having a similar fucked up background and almost all of them are sociopaths, except for Hida, and all the characters had perfect voice acting.
characters 10/10
enjoyment: 7/10 only because i cant really say that I enjoyed it, i think i need a therapist after this emotional r*pe
overall: 10/10 wouldnt watch again go ahead and rewatch it if you are a masochist for me it was a good one time experience now i need something chill and cute to brain wash me out of this.
