Agreed with previous posters. Physics engine, although good, does not help with a sports oriented game. If the movement could be more controlled (no double touches) this would make for a much better game. Assuming this is fixed this game would be addictive.
Agreed with previous posters. Difficulty is disproportionate to the start of the game. Perhaps you can simply graduate the game with levels building up to your original idea.
Although a sound concept, it is a bit too difficult to simply play and the curve ramps steeply from the beginning. Perhaps less opponents might help to get the hang of the game.