I certainly have no complaints, its everything that was advertised and more when I pre-ordered almost 3-1/2 years ago.
However, I constantly find myself wanting to use higher ISO's for extreme low light images, and that is the feature that would cause me to upgrade more than a better autofocus, even though that is a very desirable feature. Thats why I'm interested in the 1Dx, and wonder at its actual usable ISO for raw output.
As a wedding photog, I have been stuck with the 5D II for 3 years with no better choice that can provide me a better balance between IQ, ISO, and AF. I don't like its AF, but I can't live with 7D's IQ. I like 1D4's ISO, but I can't live with its cropped sensor. I like 1Ds3's IQ and AF, but I can't live with its ISO.
So naturally, I have high hope on 1D X as they claim it's the best-of-all-time all-around flagship from Canon, with the understanding that 18MP is no big difference to 21MP. And like what Mt Spokane said, ISO is the BIG thing for wedding togs. 1D X sounds like the ultimate answer.
But as a landscape shooting lover, another side of me also wants the highest MP and DR possible, while that side of me can safely ignores ISO, AF, etc.
I think there is no one single silver bullet that kills all. At least not for me. I want both 1D X (if works as claimed) and 5D III (or the next FF with whatever name)!!!