Good concept
A caveman riding a skateboard. Its definatly original and i know my skateboarding games. Really good, just a bit of polish in those small nooks and crannies and you there with a pretty rockin game. Try adding some stats onto the skateboards instead of just saying 'this take more points therefore its better' I want to be able to see that it is better, that or, just changing design and getting upgrade points.
The final change I would make, is a story line of some sort. Like your not the only caveman that can skate. Make some tournements and races and challenges. Make it more than just someone skating, make it an experience.
Done.