Just picked one up today, had a bit of time to play with it indoors.
First impressions are very good. It handles well; zoom and, more importantly, focus rings operate very smoothly with slight damping and very little dead-play from one direction to another so MF is quite usable (~150 degrees end to end) and much better than on the f/2.8 version I passed on because of sticky MF feel.
AF is quiet and fast, especially when the 3m and beyond limiter switch is on. AF accuracy in low light, using center (cross type) AF point on a D5100 body was spot on at all distances between MFD of about 1m to about 8m I had available.
The VR (optical stabilization) worked very well also, getting pixel-sharp handheld shots at 200mm and 1/15s with no problem. I suspect it could go even slower and still maintain a reasonable keeper rate.
Still have to do stop-down focus shift tests, check the bokeh, CA and corner shading on FF but so far, so good. I'm looking forward to putting it to more tests and then shooting some real subjects with it. The smaller size and reduced weight are pleasant changes from hauling around the big 2.8 glass. (altho the new Tamron 2.8 is interesting and will be considered as an option for my F-mount systems)
I did not opt for the very pricey OEM tripod mount. I'll wait until there's a better value alternative but I would deem it a necessary item if using this lens with a lightweight body like the consumer-oriented D5100 or similar. It's just too much mass and length to hang off the end of a plastic body when using a tripod. It might be OK when mounted on a more substantial body like the D800 or other semi-pro or pro chassis.
Since I rarely use my EF 70-200 f/2.8 L 2 wide open, this smaller, lighter, and possibly as-sharp option may supplant one more bit of my Canon kit. The latest Canon classic fast zoom has been disappointing me with ugly bokeh too often anyway. I didn't use the EF 70-200/4 IS so can't compare it.
So if any Nikon users are considering this lens... YES, it's certainly worth considering.