DPReview throws no small amount of praise at the foot of the D800, but they do levy a couple of good points against it. First, this has the absolute best images quality of any Full-Frame camera on the market. Everything right down to its high-ISO performance is stunning. It doesn't quite match the Pentax 645d in resolution, but that is to be expected. It is still far more than almost anyone could ever want, and frankly, I'd rather have this than the Pentax for almost any kind of shooting.
Ergonomics are excellent, with a similar set-up to the D700. The viewfinder is good. And goodies like uncompressed HDMI video sweeten the pot to the point of cake batter. This is the first camera in a long while where I can't really think of anything wrong with it. This will be a world-class camera for a decade.
As I mentioned, DPReview does point out a few faults, if you can call them that. First, the continuous shutter is a bit slow at only 4fps. You can get 6fps in reduced resolution mode, but why would you want reduced resolution? Isn't that the point? To me, this isn't much of a problem. I'm more concerned with the buffer, and fine JPEG's let the camera go for a good ten seconds before filling it. If you do that in spurts, you'll likely never hit the limit.
While the slow continuous shutter eliminates the possibility that this camera can ever be the ultimate all-rounder, it still would be more than a match for damn-near everyone. Nikon has taken everything great about the classic SLR layout and made it better. Nikon appears to have learned from their mistake with the hilariously overpriced Nikon D3X and delivered a world-class camera at a price that almost any serious enthusiast can afford.
As I've said before, I'm still going to wait to see what Sony produces. I'm absolutely leaving Canon's system, no doubts about that anymore, and the cross-compatibility of Sony's A-lenses and NEX mount are a very attractive proposition, even in the face of the D800. Olympus' great showing with the E-M5 will keep me in the 4/3 system, and really, the only place to go from there is Full-Frame, which I guess negates the NEX advantage. Nikon or Sony. Decisions, decisions.