The most unique feature that I found on the D700 (when compared to my D300) is that the cyclic rate does NOT slow when shooting in RAW 14-bit. On my D300, with the MB-D10 attached, the cyclic rate (fps) is 8 fps in 12-bit, but slows considerably in 14-bit. The D700 maintains its top speed of 8 fps (with MB-D10) regardless of bit depth.
I find the D700 easy to use, but coming from the D300 (D2H & D1H before that), the menus and functions are very much the same, so there was no learning curve involved.