The game has been reviewed as a major time suck.
Don't get me wrong, the game doesn't suck, it just sucks my (and 70 million other players') time.
I was playing with my iPad and in Desert-stage and managed to land on front wheel with a motocross bike. The trouble was, that it was evenly balanced. It wouldn't fall on either side, it just stuck there no matter what I did. Eventually I just run out of fuel. See the pic!