A very good telephoto zoom that I found most useful for birds at the beach and also worked quite well for portraits when used at shorter focal lengths. I'd prefer the 80-400 VR for birds but at $1,600 or so the bird lens must wait. To some extent this one is made obsolete by the 18-200 VR lens, as this one gives you 100 more millimeters and you give up VR.
This lens is very sharp as you can see by the sample photographs. It extends quite a bit during zooming.
A cheaper cousin exists that is much less durable and lacks the ED element. I have not tested it but I'll stick to metal mounts for everything.
Letter soup: