I've only had the lens a couple of weeks, but I'm happy with the level of sharpness, and detail, as its my first telephoto lens, I cant give an assessment of auto focus speed but I haven't had any concerns with my wildlife photography as yet.
I would say the lens hood is very poor, hence only four stars, its fallen off the lens a couple of times, and a little fiddly to attach and reverse when not using the lens.