At the price point it's very tempting.
Reports I have read, from Lensrentals.com and a couple of wildlife shooter blogs, are that it's strong up to 500mm but past that it gets soft unless you are at around F16 or greater.
Net, it's a great lens in good to bright light, not such a good lens in low light. The tests were all on Canon cameras, as it appears not many of the Nikon units have shipped. All the Canon cameras were full frame.
I still feel this lens would be a great companion on the D800 family in DX mode for most wildlife. My local shop has 3 coming supposedly next week, 1 is Nikon mount, so I am hoping to stop by to try it.
The image stabilization seems to be excellent, AF a bit slow, but overall appears to be a great value for the price point, and 1.3K or 1.6K less than the Nikon 80 -400 (new version) I can't remember if that lens is 2.3 or 2.6K.
Paul