A nice little platformer. I liked the overall feel and it was very playable all the way through to the end. Nice job wrapping it all up and polishing!
The controls felt a little bit clunky. Some acceleration and deceleration would help. Maybe also less overall speed on the player and some control over jump force -- applying it over time while the button is held.
The sound was pretty harsh and loud, so next time I would try toning that down a little bit. "softer" sounds tend to work best for thing that are heard often like jumping and -- in this case -- dying. :D
I don't personally mind it but it did feel like I got set back kind of far to the nearest checkpoint in a few places. It might be nice to try to put the hardest jumps close to the checkpoints to make iteration a little bit easier on the player.
Overall great work!