Since having my 5Dmkii and all of my lenses stolen a few months ago I've been trying everything out and doing lots of research. I was an inch away from replacing with the mkiii but in the end the D800e won. I was very nearly put off by the temporary D3200 and 35mm f/1.8g combo as it was soft (to my eyes) and way too noisy, badly noisy. I had thought that some of the hype surrounding the D3200 was misplaced and wondered equally if the hype surrounding the D800 was also over the top.
Anyway, I got the D800e and took it around to my Dad's as he has a mkii and we compared shots with both cameras having similar lenses mounted on to tripods. Each using a 24-70 Canon/Nikon lens. The difference was breathtaking. I was expecting to be seeing similar results but just larger, i.e. with more resolution. I wasn't expecting the clarity to be so, so much better. Not marginal, not better but way better. Highlights took far more effort to blow out and the shadows were so good. The difference was so great my Dad went straight out and bought a D800 himself. He won't spend money on anything if he can help it. I can't over emphasise just how much better the IQ is.
I don't like saying any of this as I still love the Canon lens line up. If everything hadn't happened this way I would have got the mkiii as I had some great lenses and prefer the way the Canon bodies work. It's not easy learning a new system but then again getting comfortable isn't good. I really hope that Canon will fight back.