My "Where is it? - Smart Kids Edition" game was written in Cocos2D-iPhone V1.0x, and I got quite a lot of problems with every iOS version update.
Spent some time recently playing around with the new Sprite Kit from Apple, although it has the limitation for iOS7 only, I am quite surprise how simple and easy to use, and all the objects and concepts are quite similar to Cocos2D-iPhone (did someone copy something? I don't know...)
After I finished the current project, I will definitely try to port my game to Sprite Kit!