Gameplay wise, there are a lot of blind jumps and I think that makes some parts of the game more frustrating than fun. Spike collision feels too big, especially on short platforms that have spikes, making it very hard to land on them without dying. In the level before the last, the speed of the horizontal moving platforms is very close to the player speed, making it seem like you aren't moving. Also when standing on moving platforms, the player doesn't move with the platform which might have been an intentional decision but it doesn't feel right.
As for audio, a slower and less distracting sound could have been chosen for the ticking of the level timer in my opinion.