Its ok

Game freezes often and youll lose your progress within a level so you have to close the app and reopen it. Levels have time restraints on when you can start or you have to have a certain amount of coins to unlock the level. Some levels are really hard to beat with the birds provided, even with the boosts. And sometimes you can watch an ad to get a tip on how to beat the level or use coins. Some levels you cant unlock because you need a certain amount of feathers or fruit but they are normally an outrageous amount and its hard to see them within the levels to try and get them.

SongzSweetie about Angry Birds Rio, v2.6.2