This series, in my opinion, is one of the few that manage to have a streak of episodes near the end that all seem to be better than the last and have you wanting more for 5 or so episodes. I will admit that the middle of the series starts to drag a little bit after a strong opening, but it is more than worth it.
Story: This series, although not completely original in some of their major themes, does a great job mixing together previously seperate themes while driving the plot with interesting devices and characters. While often making you ask for more at the end of an episode, they mix together great pacing, writing and execution in general to make an interesting story with several ingenious plot twists.
Animation: This series, to say the very least, has extremely interesting character designs that are very unique. They did a good job with all the gore they managed to throw in, on top of the obvious sense of fear they managed to instill in characters in the proper times. I never noticed any flow problems and personally loved the interesting character designs.
Sound: This series had a very solid mix of good OPs and EDs, along with a few all-star VAs. The sound track itself was well made and put together quite well, but it wasn't to the point that I recall an awe-inspiring moment.
Characters: This series did a very good job developing several characters while having a large number of very rememberable static characters taking key spots in the story. The series uses a large range of characters with obviously different thought proccesses that clash together in a very interesting way. While having believable characters that range from the type you love to hate to broken souls, to those that will stick to their ideals even if means death to themselves, the series does a great job with its portrayal of strife and action.
Overall: If you like mystery, horror, gore type series, then this is a must see. With a large number of good characters, a compelling story, and some great twist and turns, this is just, overall, a very solid series.