The music loop really suits and the backgrounds are really nice . The main character is suitably cute and the sound fx really fit them. The first level's platforms don't quite fit the scene. I expected a grassy flooring similar to the background and such rather than the checkered, sonic two like platforms. On the plus side they were easy to spot and didn't get lost.
Level design is good. I enjoy finding little secrets.
The jump floats. Consider the time the player takes to reach the top of a jump, how long they stay up there, and how long they take to descend. Ideally a nice curve with about a quarter of a second at the top. As you change the jump, the level design has to change. Consider designing levels in a grid. Get the platforming controls nailed before the level design.
Another point that has already been said: If I lose my ability to fight enemies when I get hit the level should still be obviously do-able without that power or the power should be recoverable.