There's a lot I like about this game, the platforming is solid, and although some of the slippery sections were a bit frustrating at first it was clear how to complete the level successfully.
The theme implementation was clear and obvious throughout - The more items you have the smaller your jump, but throw an item away too early and you may need to find an alternative way to the finish.
The music and art were fantastic, I especially liked the final sequence of the sunrise over the mountain while turning everything from black and white to colour.
I found the transitions between levels was a bit odd, there were a few levels where the player started off the screen, and the player is fully controllable while the old stage fades out and the new one fades in. I would recommend adding to the code where the animations are played to await the animation finished signals which should prevent any player input until the animation completes.
Hope the feedback is useful :)