The biggest gap for photographers using iPad is Lightroom-like photo management apps. iPad's built-in Photos app is laughably simple at best (iOS 5 included) and while there are several 3rd party apps, I have yet to see one that can (1) import RAW and JPG images, (2) tag, geocode (from geocache), and rate, (3) basic image processing, (4) sync against popular Mac photo management apps such as Photoshop Lightroom, Aperture, and iPhoto, and (5) share against popular photo sharing services or upload to one's own hosting service.
When and if Adobe makes such app (Lightroom for iPad), or Apple for that matter, I'd buy it in an instant.