i use camera genius app this app features are good. Refer this link Camera Genius for iPhone, iPod touch (4th generation), iPad 2 Wi-Fi, and iPad 2 Wi-Fi + 3G on the iTunes App Store
I used camera+. That app has lots of professional effects. Highly recommended!
I love Camera+ and Instagram. Camera+ is the better app though
I use Camera+ and Camera Genius, but Camera+ is probably my favorite. I also really like DerManDer, which allowed you to take panoramic pictures, including full 360 degree views. Its an awesome FREE app, and run surprisingly smooth and fast.