The real reason why Nikon put a 36 megapickle sensor in the D800, is because Canon are selling so many more cameras than Nikon, and Nikon was depserate to have some extraordinary headline in order to try and get sales, even if that meant that the camera is lacking in the features that TURE PHOTOGRAPHERS really want and need.
No decent photographer needs even 22mp, but 36 is just asking for trouble as high ISO shooting is affected, and the FPS of the D800 is sorely lacking.
The 5D3 is a very well rounded camera and very useful for anyone from pros down.
It's a camera you do almost anything with from landscapes, to action - even in the dark, to portraits and the most demanding of all, weddings.
We'll see what sells more in a few months from now, the Nikon D800 or the 5D3.
I bet the 5D3 outsells it by a large margin just as every Canon outsells the equivalent Nikon model now.
From many of the photos I've seen, especially ones taken using high ISO settings, I think the Canon is superior.
And no, I Don't have a 5D3, or even have one on order.
Anyway, by the time you have to buy the Nikon software, which you get for free with the Canon, there isn't much of a price difference.