I had a 5D2 before which I sold in November, always had half an eye on a D700 as 'The Still Photographer's Camera' but the used prices are often £900-1100, for which you could get a D600, so it had to be a good deal for me to pick one up.
Initial impressions compared to 5D2 are that it feels a lot heavier and more solid in the hand, it also seems more responsive...and the shutter sound is great, SNAP!