The physics are pretty great, though sometimes my ball wouldn't stick. I got a bit frustrated with some parts, since I had to try to hit the stick and move keys at the same time.
What really won me over though is the wonderful little expressions. I loved the happy faces as they won and the scared/dead faces as they fell. That really helped me connect with the characters and push through to the end (I thought the black level was the last one and almost gave up). So yeah, the charm of the game kept me going, along with the fun physics. Nice work. :)