I honestly love the original story so I may have a bias towards this but I defnitely feel I wouldn't have enjoyed this as much if I hadn't read Kafka's story first. I really loved the animation, it really gave the feel that I believe that Kafka was looking for, an interpretation that did the story justice far as the artwork. My only issue with it was it just seemed lacking..it felt rushed, I know in the story it doesn't get deep into the characters too much but i kind of felt like the story and plot was rushed because I didn't have the same reaction as I did when I read the story, it didn't hit me as deeply. The artwork seemed to be the main focus in my opinion and I wonder if the creator of this was forced to fit that 20 min or so mark because I felt like things just could have been done better but that is just my personal opinion. Anyways I still really enjoyed this, my only advice would be to read his story before you watch this, its great:)
That's the link I used to read the story before hand as the other reviewer MechaRainbow suggested I do before hand, which I usually recommend but it doesn't really matter either way.
Pros: Abnormal story. Child choir.
Cons: Almost everything else.
The anime follows the story pretty damn close but it doesn't make a weird stupid story and better. The fact that the animation is some fun house mirror room doesn't improve the story either. Um, not really worth watching.