Great critique by Lukas Mathis of the many confusing, non-obvious buttons and gesture controls in iPhoto for iOS.
I haven't used the app on an iPad yet, but I found it maddening to use on an iPhone. Not only is the UI as confusing as Mathis writes, but it ends up that editing 8 megapixel photos on an iPhone 4S in real time is slow. Too slow.
I plan to give it another try when my new iPad arrives on Friday, but right now I can't imagine using this app for anything real.