While I have not read the original literature for Arashi No Yoru Ni ("One Stormy Night"), I can say that I've watched the feature-length anime.
The film overall is pretty well done, art and story. This is probably my favorite anime movie that I've stumbled upon this year (another contender was Chirin no Suzu, a similar anime). The voice acting was well chosen (the Japanese), and the backdrops are beautifully done and surprisingly detailed. The story has a way of reeling you in by making you actually care about the characters. While it would have been possible to flesh them out a little bit more, they're definitely not two-dimensional.
I recommend this movie to the open-minded anime lovers.