But don't get me wrong, I am not in particular bashing Nikon here and I think that the D800 is probably the best camera in the - well 35mmm heritage shooting gear market place.
But a milestone?
Such a long posting for such a weak message?
If d800 is the best 35mm DSLR, and at a very moderate price, this can easily be called a milestone. Virtually every review so far has pointed out that colour, DR and resolution are superb, many have shown that it rivals MF cameras (much more expensive) in more than one or two respects.
It has often been said that putting more pixels on the same surface in not revolutionary etc. But people expect probably a bit too much. Compare the d800 to a 6-8 year old one, and you may start to see that the amount of evolution over the years in also a revolution.
Bayer Sensors may technically not be perfect, because they have to interpolate colour for the surrounding pixels. But as pixels get smaller and denser, the colour information gets more and more precise, fine detail is better rendered, specially if noise and DR are not getting worse (which is not the case for the d800). In other words: The higher the pixel count goes (noise kept low and DR high), the less relevant the Bayer disadvantage will get. Add RAW converters that keep getting better and better and there is less and less to critizise.
I am not a sensor expert, but I have read - several times - that inside a Foveon based camera the amount of processing and calculating (with highly complex algorithms) is higher than in a Bayer sensor. In theory the Bayer filter approach seems not very perfect, but in practice it works pretty well. And it is telling that noone so far has presented an approach that delivers results that are - all counted in - better.
Bottom of the line seems that in order to get better image quality (in a much more limited types of shooting conditions), you have to invest at least 5x as much money, lenses included even more. To make such a camera available for under 3000 bucks can be easily called a milestone. I have seen detailed comparisions between the Leica S2 and the d800 that showed that the Leica struggles to come out as the better camera: Some slight advantages here, some weaker points there... If you count in the number of situations (low light, fast shooting required, availability of different and specialized lenses) where the DSLR (d800) is superior, it looks like a real winner here. To ask 15000 for a camera and 4-5000 for a lens (that is optically excellent, as in the Leica S2 system) is hardly revolutionary.
So I think - as most reviewers who tested the d800 so far - that the d800 is pretty much an important milestone. Although I do not have one (yet).