Physics are nice. Game is simple to understand, but very difficult like everyone else said. I've beaten all 24 levels in 204 deaths. Instead of starting extremely easy to extremely hard you could have made different modes.
Some music would be nice, especially for the last level. Maybe add a death count too. A button to return to the level select screen is also a good idea. A short story in the beginning would be nice too because I didn't even know there was a princess.
Very good game, couldn't get pass the level 17 though, I hate those things where you just have to keep trying and trying until your finger get the correct pixel to start. Not saying it's a bad thing, just not mine.