A very good, but deeply flawed game.
I love the game. I went through it, and even more. But in the end, you really need to work more on it. The controls should be at their best with a keyboard. No matter if you want us to use an Xbox360 controller or not, you're on a PC. Meat Boy was way too sensitive, and in a game that hard, you don't want that. Plus, you really need to cut down a bit on the collision boxes, because most of the time you wouldn't even touch something that kills you, but would die anyway, and again, in a game like this, you don't want that.
As many people said, a mute button would be welcomed. And I'd suggest a bigger screen, because it is awfully small in anything larger than 1024*768.
But hey, keep up the good work, and please do something about the issues if you ever release a sequel, because your game isn't very far from being excellent.