A lot of people think the d800 replaces the d700, it doesn't, if anything they're both separate product lines and the d800 is the replacement for the d3x

36 mp is a lot of pixels and it can fill up your hard drive pretty quickly and bring your computer to a crawl- there's a reason the professional d4 'only' has 16mp.
More megapixels is nice for landscape shooters needing maximum detail, and big cropping- but really sometimes you don't need that many and the d700 sits in the sweet spot of low light image quality, af performance, and at a fantastic price.

You can still make 30x20" gallery sized prints with this camera, and the AF system is flawless, simple and effective- everything the 5d2 was not, nikon shooters had it good and even today the d700 is a great camera to purchase because the d3 and d4 are very big cameras, and the d800 is expensive and a computer killer- this leaves the d700 firmly where it has always sat, as a professional camera for every day professional use, light in weight but not light on features.

Although not the latest and greatest there is no reason that you can't take award winning images, or do professional photography with a d700- it was always a great camera and now for what it costs it's an even better camera. Highly recommended