This is an awesome game, with great graphics on my Asus Transformer and good replayability. I've played through on easy and medium, now i'm going through on hard.
I'd really love more levels for the game, and i'd be happy to pay for them. If there are no in-app purchases on Android and it means downloading a new version, no problem.
It'd be nice if when you changed your difficulty it showed you which is the next map to play. Right now if you beat it in easy, then set the difficulty to hard, to start the next hard level you have to scroll back to work out manually which one to play. That's a minor quibble.