My biggest issue with the D800 was the shortage of Nikon lenses that could take advantage of the 36mp. I've been so use to the wide array of really good Canon lenses that it came as a bit of a suprise when I started hunting for a Nikon equivalent to the 24-105mm L, and my 100-400mmL.
Nikon does have the excellent 14-24, the 24-70mm, and the 70-200mm lenses, and their 85mm f/1.4 is supurb. For non super telephoto lenses, it starts to go downhill rapidly from there. I can live with the noisy high ISO by pouring on the NR, there is, afterall, a lot of resolution to trade off with NR.
The D800 also has some better features focus points that light up, f/8 autofocus, and others. Its just a evolution of the D700. It is a great camera and deserves much of the alocades, but I really do not see it as a game changer.
In the final analysis, it was the lens situation that caused me to sell it, not the body itself. Nikon needs to expand its lens development. It got into a hole when producing only DX bodies and needs to claw its way out. At the current rate, they are not likely to catch Canon, but they will have 2-3 lenses that are better while Canon has a ton of lenses better than their counterparts.