Gus,
Compared to the D70/s, the viewfinder is a strong step forward. I have not used a D2X so cannot compare. The D70 gave me the impression of looking through a tunnel -- the D200 does not.
While I felt the move from the D100 to the D70 was essentially lateral, the D200 feels more robust and capable in all significant areas. Autofocus system is improved and hunts less, higher ISO images (when well exposed) are useful even up to 3200 ISO so long as you don't mind a small bit of what appears to be film grain. Continuous shooting at 5fps beats 3fps.
As for sharpness, I have not compared D70 to D200 yet. Most of my work is shot in RAW to avoid the in camera jpeg engine. The D200 images may be slightly less sharp than the D70 in jpeg from the camera -- then again, the D200 seems to have a brighter tone curve which makes out of the box images immediately useable where the D70 almost always required some tweaking to bring up muddy colors and contrast.
I'll be glad to address any other questions. My overall impression is that Nikon has a winner here.
Houston