Too bad the entire gameplay is a 100% miss: You have to wait or pay to retry levels after a while. This goes completely against everything that defines angry birds gameplay, which for me is to instantly re-start the level if I'm not satisfied with the first bird shoot.
Absolutely ruins it.
I'd much rather pay $X upfront for unlimited gameplay. Now it just feels like they're trying to cheat me out of real money every 15 minutes feeding some kind of virtual slot machine. :(