had a visit from a friend with a D800, with just a kit lens on it. A few first impressions:
- very impressive, very easy to use, lots of bells and whistles, could be a great "one stop camera"
- has lots of resolution , very fast previews, good high ISO
- its a heavy camera
- needs a better lens (it really stunk with the stock plasticy lens. Needs good Nikon or Zeiss glass)
- suffers all the stability issues that the MFDB cameras do - with so much resolution, it calls for stability. Its hard to hold at eye level and get that. To this end, there is a Nikon PDF on tech'l tips on how to use the camera, including info on diffraction, etc.
By the time you add good lens and deal with stability, you aren't that far away from the use pattern of a MFDB solution. Lots of people will make lots of noise sbout how great this camera is, and in many ways it is, but.... in some ways, I'm not so sure. Its a great value, but operationally, it may prove to be a bit of a challenge. Not huge, but more than one might think. You can't hold it at the eye all day long. At least I can't.
Viewfinder is OK, not great. Resolution seems fantastic, video great, preview super. Tonalitiy - hard to tell. My guess is the MFDB (Leaf for example) are better.
The real fact is that a camera with this many MP requires a certain approach and technique. Once you do that, it doesn't matter what the camera is. Its a combination of the form factor and the use pattern that governs how the camera can be used. There is no way around this. So - as a replacement for a Canon, or for having lots of pixels, wonderful. But add the lens, add the weight, add the stability, and think long and hard before you abandon MFDB. The costs aren't comparable, but the use pattern is what governs. I like the flexibility of finders, of film, of rotating sensors and the better lenses (Schneiders). If one were going to a smaller form, the S2 Leica (at 10x the price!) seems better.
In short, the D800 may well be a great camera, but use of all its performance may be harder than one first thinks.