You know the story background, its on ANN. I'll just write my thoughts.
Story: Surprisingly good. Good in the sense that its very unique. I liked how they attempted to keep a balance of economics and shounen. It would be better if it was 24 episodes, since the ending was sort of abrupt and left a few plotholes. Moreover, it loses points on using a motif used over and over again (I'll spoil it if I say it).
Art: Not bad. But the CG got very noticeable at a handfull of points, which bugs me. Also the animation wasn't very fluid (Thank you PA Works for making my standards very high now).
Sound: Another outstanding soundtrack, as expected from Taku Iwasaki (gurren lagann, soul eater). Opening and ending were amazing too. VA was pretty decent too. Also A-A-A-A-A-A-ANGEL.
Character: Liked how it was a poor college boy and not some angsty teenager. But I feel the development for the protagonist was a bit rushed. Also forced drama.
Actually, you know what, just get the OST and forget about the anime. You won't be missing out on much anyways.