This anime is pretty good. It will put you in tears (particularly in the final episode). Get ready for your tissues if you're going to watch this. The story is well thought out though simple. It mostly consist of slow and serious parts especially at the end with few light hearted ones to balance things out. The characters are well defined and doesn't go too over the top. Character development is good too. They change at least slightly as the show progresses though a huge bulk of it happens in the final episode. The art here is fine for 2011. I don't think it pushes anything amazing. The music is pretty good especially the OP/ED. It fits to the scene that is in play.
It's a great show (Not sure if this is the best of 2011 due to heavy competition). I recommend to anyone that would like to cry or wants a good drama.
Story 10/10
Art 8/10
Sound 9/10
Characters 10/10