I went through this when buying my D800
Simple answer is YES its a brilliant camera.
I tried it beside the D600 but the poor focus on the D600 in comparison to the D800 made it a no brainer.
Awesome file sizes and with them being so large cropping into images is no problem.
You will need plenty of fast cards,minimum class 10.
I've never heard anyone complain about D600 focus in fact DP review says:
"In good light, the D600's AF system proved very capable in all of the environments in which we used it. In the hundreds of frames that we've shot with the camera, including images taken at night and in very poor interior lighting, only a handful are anything other than totally sharp. As usual, if you're working in marginal light the central AF point is your best bet, but in normal everyday shooting, the D600's AF system is very capable." although they do mention that the D800 is better in very low light (-2ev).
In my experience you can focus and shoot with the D800 at levels where it is too dark to see what you are shooting [but I do use fast prime lenses].