The art is beautiful, but I think there are a couple methods that can immediately improve the gameplay. I don't intend to sound harsh, just want to help :)
- The jump-up is too tight for how small the platforms are. I think if the jumping-up was a little more loose then players can control their positioning a lot better. The jump-down is good though, a real snappy feel
- It is not clear what the platforms are, maybe if something fell on the musical notes to show that they can be stood on it would help new players
- The camera is pretty snappy -- that can be good, but in this case it is really harsh. Consider lowering the speed of the smooth follow, or just don't translate the camera at all when the character changes directions.
In any case, the art work is really nice, I hope you find my suggestions helpful. Good luck!