Yeah I played it on an iphone, it was a good distraction, but not anything I haven't seen done a million times before in other basic flash games. (In fact it's almost identical to that catapult castle flash game, and the castle one makes more sense.)
I think it's just one of the first flash games of that style to reach the casual market. Someone found it who has had no other experience with these types of casual games, got addicted, believing it to be something amazingly original told their friends, it slowly snowballed, until someone famous heard about it and mentioned it, and suddenly millions of people following them gave it a go and also got addicted.
It is a very well made and polished game, but it doesn't innovate or add anything to the gaming industry. A case of being in the right place at the right time.