A bird photographer in Honduras, Bobby Handal, posted pictures he had taken with his AF-S VR 70-300 at DPReview (Nikon 1 Forum), which led me to get one, too. A nice zoom, useable for everything from a Nikon 1 camera (CX format), D3200 (DX), or a D600 (FX). Probably works well on other cameras, but I have not tried it!
It is not at its very best for birds in flight, but as soon as the birds are on the ground, in a tree, or swimming, its pretty awesome. The VR (vibration reduction) is amazing on this lens, and on my V1 it equals a lens of about 200-800 on the D600.
The only negative part is that it is not the lightest of 70-300 on the market, but the results with it is outstanding, considering it relatively low price!
Mine works very well with my Kenko 1.4X Teleplus Pro 300!