Many good things have already been said and I agree with most of the feedback (both positive and negative) that other users have, so I won't repeat them. However, I want to stress the horrible controls for the smoke rings. I was on the verge of quitting a number of times and actually ended up downloading a program to make a macro for the click-timing. I have no problem that a game is hard or that a puzzle is hard, but when you fail a level on a puzzle game repeatedly, not because of the puzzle but because of the controls I say that this is a serious flaw.
Otherwise, a brilliant game.