Very cool
Pretty damn awesome. Style, music, animation, story, use of color and character design: all great.
A couple things though.
1. I would have preferred it if the cube hadn't shed a tear--vibrating or some other reaction might have been more surreal and sinister.
2. I wish you had made variations on the cube's *ching* sound. The sound effect is so standard that it took my mind out of the movie each time. That, and some progressive distortion on it might have been interesting.
3. It seems you timed the end text to finish up with the lound boom at the end of the soundtrack. However, I would have liked to be able to skip to the next block of text when done (I found myself waiting for the change for several seconds). Others might not have caught all the text.