Looked at one, for the price, wasn't my cup of tea. At that price range, I would rather go with the D800.
For my 2 cents worth, it still boils down to the fact that Nikon still has not brought out a true successor to the D700, which I think they got darned near perfect at the time. The D800 is slower, the D600 is not as sturdy and lacks some basic features that the D700 has, and the Df, well, it lack basics like dual card slots.
I think Nikon keeps dancing around the D700. I don't know what their thinking is, but I wonder, in some cases, is the panning of the Df is related directly or indirectly to the fact that many of us are disappointed in Nikon for not coming out with a simple upgrade to the D700?