I'm not going to spoil anything, but the really disappointing part was the ending: there's nothing worse than a show that doesn't know what to do with itself, or doesn't have the courage to drive itself to a definite goal.
Art: Nothing to say here, it hasn't left me open-mouthed, but it's certainly high quality. The CGI is scarce and well used, with no attempt to render the characters with it, which is a good thing in my opinion. The characters stand out from each other very well and the sceneries are ok; I didn't notice any particular fall in quality or in the amount of details.
Sound: Most of this will fall under personal preference, but I personally disliked the opening and ending: I found them extremely generic and not particularly pleasant to listen; I never once was compelled to let them run from start to end after having heard them once.
As for the soundtrack as a whole, while still not particularly remarkable, it had its moments and it was noticeable during the action scenes, with its main flaw possibly being variety: there weren't many different tracks and the fact that some of them were reused in very similar situations time and again made the similarities in those scenes easier to notice, which draws away from the enjoyment.
Characters: In my opinion, the real strength of the show. Though the bane of modern anime, archetypes, are still present, the characters themselves are evidently not slaves to them and at least some of them showed a very good characterisation that was definitely remarkable to me, and surprised me at times during twists in the plot. The protagonist is definitely not one-dimensional and that is a really, really important pillar for any show to have. The major flaw I could find in this area of the show must be that, probably because of production and running time, some characters were skimmed upon very superficially and others didn't have the screen time to show their potential. I think the show would have benefit from a slightly longer format, perhaps around 15 episodes instead of 11.
Enjoyment: Action sequences were definitely good, the moves and styles of every character were noticeably diverse and not monotonous; again nothing that made me stop in awe compared to other shows I've seen, but that's really the only flaw.
Comedy is present to some extent and I must say it made me giggle from time to time, which, as a person with a twisted sense of humour and about the same tendency to laugh of a cold rock underwater, I found it amusing enough to consider it good.
Character relations aren't stereotyped, with very few exceptions, and that was certainly good to see.
