Effective platformer with decent controls and some fun surprises. I loved the Goomba's shoe! :)
The graphics are a little rough. One of the hues (the dark green) seemed underused, and I couldn't tell what all the objects were. Also, the vertically moving objects seemed to travel too fast, although of course the player can figure out the timing through trial and error.
Lastly, note that enemies do not respawn after you die, so you can cheese the difficulty a bit by taking enemies with you.