I feel that this is a beautiful game! I really enjoyed the short run time. It was a chalange. I did feel that jumping was a bit unfair.
When I first started I didn't know I could jump in the air. When I did jump in the air I couldn't tell how many times I had till I couldn't anymore. Please add a meter showing how much jump power you have.
Collectable items are small and hard to see. Please change any items which are red to be green just for contrast also make them easier to spot the glitter particles are okay but still not quite enough. Please make the health bar green it blends in too much being red and move it to the top of the screen and make it larger.
The lightning power-up is cool but not really nessisary also you can't tell where you are shooting and when you hit something. I couldn't consistantly use it to attack anything.
The battle with the spider at about the midpoint had a bullet time effect. This was disorianting as well as sometimes after using my attack the game slowed down and most of the time it didn't.
I ran this on Linux with WINE it worked just fine other then the the slow downs.
At this point in development I don't feel that there is $5 worth of content.