I can't believe...
I can't believe that in a game so simple yet addictive you didn't bother to:
1)Make the background move in a loop, or move at all. That would have made it seem more hectic too. You could even have used a mask to keep the "outer" background clouds stationary.
2)Let the user select starting level. It takes forever for it to start becoming a challenge, and I just don't have the patience to do the first part all over again.
So... Umm.. Do that.