Very, very clever!
The Ricoh GXR M-mount is very, very clever and has some unique features.
You can assign direct ISO-control to the ADJ-switch, direct whitebalance selection to the zoom buttons and exposure compensation to the +/- buttons.
The focus assist mode ("peaking") can be assigned to Fn1, but what is even better: When you half-press the shutter button, the peaking-lines dissapear, giving you a clear view of the scene. When you release it, you get back the peaking-lines. On the Sony NEX-5N it is either always on or always off (or you have to go into the notorious menu to switch in on or off).
In playback mode you can zoom into a picture and then switch to the next picture at the same zoom level and zoom position! Like that you can easily compare details in a series of pictures. In all other cameras I have used so far it is the same stupid procedure: Zoom in, then out again, go to the next picture, zoom in again, etc.
Wearing my glasses, I can see 100% of the scene + all the camera information in the EVF. In the EVF of the Sony NEX-5N I only see 70-80% and I have to move around my eye (or camera or head) to see everything. Same problem in the finder of the Leica M9 (for 35mm frame and wider).
Picture quality is also very, very good, noticeably better than with the Sony NEX-5N, using the same lenses: You get more different shades and colors in dark areas.
I love the shutter sound. Quiet and dignified. Klack. Quieter than the M9, I find. I used the Ricoh during an accoustic music performance where everybody was holding their breath - nobody noticed the shutter noise. (I was really nervous that it would disturb the musician - it didn't).
The electronic shutter is completely silent, of course. But you get regular dark and bright bands in artificial lighting with gas bulbs or tubes, as the scene is scanned from top to bottom.
A 2-axis flip-out screen would be great -- not like the Sony NEX with only 1 axis, but like the Canon G12 or Panasonic GH2 with 2 rotation axis.