Beat it. Excellent game. Nice sprites and good music. At first I thought, "This weapon is way over-powered", but on screens with small platforms it ended up needing a little finesse. The boss battle on was pretty intense.
The difficulty seemed to increase as the game went on, introducing concepts along the way (hallmark of good game design, they say), but I felt the difficulty plateaued after a while. I would have liked a bit more platforming and tight spaces.
On the topic of flow, I love one part of the game where there were a few claustrophobic areas, and then to break it up you had a hallway filled with bats that you could easily beat the tar out of. Very relieving.
5/5/5/5