Some points I have noted since the switch from the D70 to the D200.
-Better Metering. Exposures more spot on especially when photographing white aircraft. The D70 more often over exposed.
-Much Much Better White Balance. The white balance on the D70 was often wrong in high contrast situations (tending towards blue/green) and needed to be corrected. But with the D200 no correction is needed, the white balance seem to be always spot on.
-Better saturation in the shots direct out of the camera. The colour level now doesn't need any tweaking on dull days like it did in the D70.
-As a results the shots straight out of the camera need a lot less work in PS
. In fact mostly what I do now is crop and straighten. Not much need for USM
as you can add sharpening from the camera. Because of the higher amount of pixels, now you can crop a lot more shots that you were a bit off on and not worry about the reduction in quality.
-Much faster to use and easier to move between settings (using shooting banks).
There are many minor details that just make it a joy to shoot with. There have been some people that have moved from the D70 to the D200 and not fully understood some of the basics of Photography. They used the programmed modes on the D70 and theres none of that on the D200. if you understand the basics you should be able to move to the D200 easily.
My first D200 photos I took of Aircraft are uploaded here, and I basically just took it out of the box and started shooting. Apart from cropping I didn't do much more to the pics and they were accepted. Wouldn't have happened with the D70.
Hope this helps