Not bad for a mobile device - Download DSLR images direct to the iPad (keeping originals on camera) in the field, edit them quickly, and then upload them direct to your FB page or Flikr, etc. All before you even pack up your gear for the night. Very nice...
App: Photogene (3 or 4 bucks) - levels, curves, sharpness, etc. Lightweight but....mobile.
(Actual size)