Two words: Pacing Issues.
It moved exceptionally slowly, and the fact that 90% of the movie was slow motion didn't help the pacing.
On the plus side, it was an interesting (albeit confusing) idea to base a movie off of. It was certainly attention grabbing enough to keep me watching through to the end, or what I guess is the beginning.
Lastly, I'd advise you to use motion and shape tweens in moderation. I know it's a bit more work to animate frame by frame, but there are some points in the movie that just looked awkward because of the use of motion and shape tweens.
Oh, and the music fit well, and was pleasing to the ears.