I think this show is overrated, I watched seriously but it was just alright.
First the storyline was good, it was unique and the built up of it was so good. And that's why after watching it, it's not worth the hype.
This anime is like they try to emphasize to the horror and kill, but I think it should not, it have a good start like SnK but they just ruined it.
But since it mostly about horror it was good for those who seek it, the art and sound are pretty great, some scene are stimulant too.
However the things I don't like the most was the characters, they're being too dreadful, bleak, dark... It's like they're all about violent and such, no story's lesson or meaning at all, well they're some but they're not good enough
Anyway, that's my thought of this anime, it was overrated and it's a waste of a great story.