Summary: This lens is a pretty good long zoom. It is not as fast at focusing as Nikon or Canon with their own brand of lenses as it usually takes two or three presses of the button to get it focused. Pentax owners don't have many aftermarket options for lenses.
Summary: Lol, I read some of the other reviews before I bought this and thought "How loud can the auto-focus be?". Well, if you're trying to be quiet, it can be REALLY loud. Even so, it takes some really great images with my K3, so I definitely recommend the lens.
Summary: Excellent lens for the price, as others have said. Picture quality is pretty incredible from distance and I have no real problems with it. A bit loud whilst auto-focusing, but if you aren't hunting I think it should be ok. Great deal, in my (amateur) opinion.