It's a very beautiful movie. It's overall animation is smooth and works well with the story the animators are depicting. Not to mention the art and use of color.
Although I've never enjoyed the use of 3-D modeling (because I just think it ruins the animation in the scene it's being used in), I thought it worked well with this movie.
I did cry like, a good three or four times here and I don't usually cry over animes. Good job, I've become Niagara falls :D.
I do agree with a lot of the other reviewers that this movie was a little rushed and it should have been turned into a 12 episode series, but I enjoyed it nonetheless.