The music, graphics and general feel of the game really come together nicely for a very pleasant experience. I really liked this game. Could easily see it turning into a sort of Katamari Damaci if developed further after the Jam.
A couple of criticisms:
Camera wasn't great, I'd have liked to be able to see what was behind me.
The definition of the Theme was stretched pretty thin here and feels more like word play than an actual design decision. It really comes down to Collect more things to get bigger, but you just described that in negative to make it fit the theme.
Other than that, really cool, good looking and fun game.