This is very preliminary, and I plan to do more testing. I received my D7000 two days ago and have been very happy with the results except for an occasional not-so-sharp image. I believe I narrowed it down to VR operation, on two VR lenses, my 16-85VR and 55-200VR.
I perceive a vertical "jump" at slower (not extremely slow) shutter speeds, which is not there if I turn VR off. The four images I have attached were all shot at F11 and ISO 100, 1/100 ss on the 16-85VR and 1/125 on the 55-200VR. I have shot many more images, both with VR on and off, with consistent results. Again, fine detail in the image (look at the small bright sunlight reflections) is smeared primarily in the vertical dimension.
I still have my D300, and it does not exhibit this problem. At first I thought it might be lens whip, but it does not occur with VR off. Has anybody else observed a similar problem? Of course I may have a defective unit, so the next step is probably contacting Nikon.
Added by edit - In vertical sequence, the images are 100% crops
16-85VR @ 85mm VR on 16-85VR @ 85mm VR off 55-200VR @ 200mm VR on 55-200VR @ 200mm VR off
The first one I had did it also... no matter how long I waited. It also had focus issues. I took it back. I have had the second one for a week and haven't opened it yet as I am still not convinced it is the best thing to come from Nikon to date. Entirely too many negatives so far. I shoot tons of sports action, and I shoot JPEG. The only decent images I have seen to date out of a D7000 have all been RAW. I'm really not into that.
After much more experimentation with a suitable target (see attached) I have come to the conclusion the problem is my fault, sort of.
It takes much longer (1-2 seconds?) for the vr to stabilize on the D700 compared to the D300, from a standing position. With a new target (see attached) and much patience I was able to obtain clean runs thru pretty much all shutter speeds, on both vr lenses.
I don’t know if it’s a different algorithm or difference in mass, but the image just dances around in the viewfinder for a LONG time and finally settles down. And if one waits long enough it will go thru the jiggle/settle down sequence again.
So at least for now the D7000 is back to being an all around great camera, certainly the most bang for the buck IMO.
“It takes much longer (1-2 seconds?) for the vr to stabilize”
This can be an advantage of decoupling focusing from the shutter release. VR detects motion, so if your shutter release does not initiate focus then you can activate the VR, and allow it to settle, by just half pressing the shutter button. Then by the time you have composed and focused, using the AE-AL button the VR will be ready to shoot.