Safe
Since I am a drummer and this game is about drumming I will give you 5 points. The idea is great! The sounds weren't bad, either. Here are my suggestions for the sequel:
Add more stuff to play on (what about a double base for instance?)
Allow the user to play your kit with the keyboard. Otherwise, you can't play the really cool beats because you can't hit anything simultaneously.
Try to improve the artwork.
Finally, it would be awesome if there was a way to switch between open hi hat and closed hi hat (for the funky beats)
I am waiting for the sequel :-)