I've had mine for a while, and mainly use it on my Nikon 1 cameras, but also on my FX camera.
It isn't quite as good as the 70-300CX, but costs less than a third!
I had the AF-S 70-300 VR before, but this lens is sharper in its long end, where my interest is (the Nikon lens is excellent in its wide end).
In low contrast situations it can have problems attaining perfect focus, thus can pump a bit.
It is nearly flawless on my FX camera, a little more hesitant on my Nikon 1 cameras.
Considering its excellent anti-shake system the lens is truly exceptional, considering its very friendly price!