1. It's an okay idea. Could be better if presented more complete with all the core features running. Hard to tell from just knocking a couple balls around. Another thing I felt was that the "shine" you did for the floor, etc, came across more like fog. Is it fog? If so, ignore that!
2. I smell tech demo more than anything I would pass on this one.
3. Inspired by Little Big Planet at all? That sack guy looks a bit too similar to the characters in LBP I think. Other than that, I'd like to see something like that I think. It's sort of like your first idea but the mechanics are a rag-doll instead of a ball.
<img src="http://tbn0.google.com/images?q=tbn:r0ecJnKAswzz7M:http://images.wikia.com/littlebigplanet/images/8/80/Sackman-large.png">