The last few episodes had some flashback to them to add drama, which I felt they could overall due without. Kouta and Yuka, were also extremely slow to realize a lot of things which was annoying, but over all I enjoyed the feel of this anime.
The atmosphere was dark from the moment the OT started to the end of the last episode. The sickening feeling you get when people who are killed simply explode into a bloody mass did not ever go away from me. I found an odd satisfaction in some deaths, while others horrified me. However, it did maintain an element of calm about it as well, like a methodical determination to achieve it's goal.
The characters were all very fun to watch, especially the dicoulous, because you never quite knew how they would react to the sometimes over zealous human emotion. Truly an interesting anime to watch.
