One of those lenses that was an extreme let-down when I first used it. Have since hiked about 40+ miles with it, use it almost always on a tripod, and absolutely love it. I've taken about 600 shots with it so far.
This is a lens that makes you sit back and say "Oh wow" when you get your shots on the 'puter screen.
It isn't very fast, and it isn't IS, which means you are using a tripod if you want to see what this thing is really capable of. It is capable of extremely sharp, beautiful images with almost 3-D quality to selective focus shots.
It should come with the tripod ring mount, shelling out another $150 after the lens is a let down, and it is necessary as the lens is just heavy enough, just long enough, to be prone to shake when on a standard camera mount tripod.
I have taken some great handheld shots at all focal lengths, but in truth this is a lens for the tripod at 200mm.
A great landscape lens, and not heavy enough to hate hiking with.
Purchase it with a clear conscience, you are getting something of real quality.