Story: It's decent, not necessarily new but it does it well even if it's rather slow around the first half. Has some very nice twists that it hints at during the show. The story would've been much better if they hadn't relied on the crappy nose-bleed echhi factor as it quickly became tired and irritating, at least for me.
Art: I have nothing to complain about here but then again there's nothing that stood out to me as well. Definitely liked that there was a lack of obvious CGI animation as that's my pet peeve with some recent anime.
Sound: Same with art, nothing to complain about, seemed well done.
Character: The characters were decently fleshed out, though Rabura was a bit bland (just my opinion though). By this point you may have noticed that I'm not particularly concerned about extensive reviews of a show as I usually get that out of the way while I'm watching it.
Enjoyment: I finished it in a single day so, yeah, it was enjoyable but I did find myself skipping five-second intervals every once in a while, so not a good sign. Would've enjoyed it more if it had taken itself more seriously.
*Spoilers and ranting ahead*
Just want to throw it out there, the ending is so good until after the death scene. They ruin the lasting feeling of sacrifice by making it seem almost arbitrary and just that it happened so whatever. If it had ended with just his sacrifice it wouldn't have been a perfect ending but it sure as hell would've been better and my ranking of the show would've been an 8 instead of a 9. Besides that they had good humor, I personally liked the cat porn joke. I did like the fact that they kind of led to Ito using the mecha by having her be really good at a game that the mecha's controls were pulled from. I hate the fact that they didn't take the story seriously. When a character dies you don't offer panties, that is in every aspect offensive, maybe not necessarily to the character but to me the viewer who is trying to take the damn ending seriously. That shit ruined the tempo of the ending and combined with all the other crappy choices made me dislike this anime. I liked aspects of this anime, which is why I'm not giving it a 3, but I would never recommend this.
