First off, excellent visuals. Nice sprites, well-animated player character, and gorgeous backgrounds! The sound is good, too. I enjoyed exploring and navigating this world.
Some suggestions for improvement:
I'd love to be able to attack with the left mouse button as an alternative.
The enemies should react a little bit when struck. This was especially an issue with the beefy mushroom dudes, who would just keep charging me even as I was striking them.
The controls are not bad, but they feel just a little bit stiff, especially the jumping/gliding. It's hard to describe exactly why.
Lastly, since the game takes place over a large area, a map would have been helpful.