All the navigation controls are on the same part of the body as the screen, so you can do just about everything other than compose a text message without opening the phone up.
Otherwise, it's aimed more at the casual carry-around crowd with a 40 percent smaller body, touch-screen focus selection, control ring exposure adjustment, a 3-inch 920k dot TFT LCD, art filters (in the smartphone app), image (or film) stabilization and 1080P 30 fps HD video.