Summary: I like using this lens for all the times my family is sitting at the kitchen table or playing in the living room. It enables me to go without flash most of the time in those situations. However, it is also a very fine lens for those times when I want to be a "serious hobbyist.
Summary: Lens is fast and images are rendered sharp. Bokeh at f4 is just awesome. HSM motor really delivers and its quiet, really quiet. Love the weight on the lens and it sits proudly on my kx unit. Would recommend this lens to anyone who is looking for a good short tele range.
Summary: This is currently my favorite lens. Echoing the other reviewers, the range is perfect for a walkaround lens and a perfect sub for the kit lens. Solid construction; it's got some weight to it. Smooth focusing, and sharp images. Macro to boot (see photos I've posted).
Summary: Best bang for the buck walkaround lens for my K-r. Had the Tamron 17-50 F2.8, but lacked the reach. The Sigma, while lacking 2.8 across its FL (but, mind you, you're not paying the exorbinant $$ that would bring), does have 2.8 at the wide end, has the 70mm reach that gives that extra that kit lens...
Summary: After a new DSLR user lives with a typical 18-55mm kit lens for a while, he or she will start running up against its limitations. Pentax makes an excellent kit lens, but even so I wished for something a bit faster that was a touch wider at one end and had somewhat more reach on the telephoto side.
Summary: I purchased this lens to replace the standard kit lens that came with the Pentax K10D. It has proven to be of exceptional quality both optically and mechanically. I have shot it under many varied situations and it continues to give me the exact results I hoped for.