Excellent game! For what it is, of course. The only real things I didn't like were the fact that if you upgrade your saw speed too much it will clip right through enemies without harming them, and that the bats will sometimes rush you right after picking an upgrade. But I'm overlooking that, because it was still really fun.
You really nailed the graphics and music, it give the perfect spooky vibe to the game.
I would love to see this expanded with a few more upgrades, like multiple saws, the ability to change the direction, maybe different types of saws?