It's really, really hard. The collision detection for the black boxes is not very good. I also think that the boxes should instantly disappear when you mouse over them instead of fading away.
Hard? Yes. World's Hardest? Nope. Not even the sequel is the world's hardest game. Meat Boy map pack is much harder. This game is still really fun though.
I guess I see why people don't like the controls, but I like them. It makes the game more challenging. It's a different type of experience that I think makes the game more fun.
Fun at first, but it gets boring quickly. The first one was only entertaining for 1 or 2 plays, and this one is too, so it's boring for me to try to unlock all the stuff.