Part of the problem:
The 5D Mark II was an easy decision when it came out. It was excellent value
The 5D Mark III faces stiff competition for camera dollars, and not just from the Nikon D800, but the D600, the Sony's, even the panasonic GH3 (for videographers).
The decision to buy the 5D III is difficult, and I have been on the fence for months. Not sure if I will ever buy one now. I still think it's a great camera, but the other options in this round may offer better value.