Very nice graphics! The crystal's animations were good, brought a feeling of life to it.
The music was fine, but didn't really fit with the gameplay and jumping sound.
The controls took a while to get used to, particularly the sliding - at first I thought it was inconsistent until I realized it took momentum from earlier jumps (even beyond death), not just the latest one.
The level before the last one was a tough one! Took a few minutes to beat. The very last one was easy though, and I think it would have been better to place it earlier to teach the player how the jumping momentum works.