Pretty good
This is a pretty awesome game, the only issue I find is the slowdown. I think if you cut down the amount of little gears that go flying, it would help with this problem, since I got the most slowdown when a bunch of those gears were onscreen.
I love your artistic style, the character designs are amazing, especially Death. The music is freaking awesome. Levels are linear, but with enough freedom of movement that it doesn't become monotonous. Well done.