skipping the jpgs because they are meaningless, I must say it is looking very good with the RAWs, but it isn't anything mindblowing like the first reports claimed it was. Clearly, it ain't a D4 or presumably, 1DX. But it is a nice balanced camera, that although rarely scores first in any given category, it places decently in most.
For my own purposes and quality standards, I find ISO12800 to the limit I'd use it since things just degrade horribly beyond that, and surely the dynamic range well on its noisedive down trajectory that is typical of high ISOs.
on a side note, the D800 is REALLY holding up well far beyond what I expected. No small feat for a 36MP monster that was supposed to be terrible. I'm actually surprised the 5DIII didn't beat it by a wider margin since it has such commanding advantage with the larger pixel pitch. Nikon/Sony really pulled a fast one with that sensor
Still, it is no question the the 5DIII is very good at ridiculous ISOs, but I'm going to look at how downsizing to 36MP->22MP assists it in closing the gap.
It is going to be a tough one for the 5DmkII studio/landscape guys. I don't see any mindblowing differences. Certainly none to justfy the price. And if you prefer good soft controlled killer light to crappy low light, then it is an even harder choice.