Just came back from a demo at the local dealer.
Here's the main points.
1. Does not have the range of features for focus tracking that are available in the D4s but this will come to pass in future firmware updates. In other words this camera is not yet ready for professional action photography.
2. No sports lens at the moment. Current 24mm to 90mm zoom is for studio and photojournalism. 70mm to 280mm lens available mid next year which will probably be when firmware updates are released to take full advantage of this lens. It will then be extremely interesting to see whether any pro is seen with it at a major sports event.
3. Very solid and very waterproof. Demo included pouring a jug of water on the camera and lens with no ill effects whatsoever. Water just rolls off the lens with zero water residue on the lens surface.
4. Fantastic colour from DNG files without tweaking. Skin tones very natural. Because it is an electronic viewfinder, any colour balance adjustments can be seen in the viewfinder because when you look into the viewfinder, you're actually seeing the image that will come off the sensor.
5. Electronic viewfinder is the best ever. Far better than Sony, Olympus and Fuji.
6. Touch screen can be used to focus. Just touch the image where you want to focus eg if you're in the studio and you want to focus on model's left eye, touch the spot and the camera will focus and shutter will fire in a split second. It's amazingly accurate and razor sharp.
I highly recommend it if you have $17,000 burning a hole in your pocket.