Angry Birds is a big fat rip-off. It's almost a perfect copy of ArmorGames's Crush the Castle, even though it's not technically by them, I couldn't be bothered to look up who it was. Point is, Crush the Castle has been on PC for years.
Cut the rope is fun, but it's annoying at times. Finding out how exactly to get all stars is a challenge. It has issues, but it's pretty awesome.
Fruit Ninja is boring. It is. I don't like it. Maybe it's personal, but I don't like.
One thing I hate about iPhone games in general is the "holiday skins". The obligatory "omg, now all characters have pumpkins for heads for only 0.79!" Now Christmas is coming up, those start popping up too. Angry birds is particularly guilty of that, promising free Christmas to those who bought Halowe'en...
I do like the fact that it's so easy to access.
If you are looking for a cool game, check out Ash. It's a nice little RPG like we used to play on the NES.