This is an old, discontinued version of a decent, lightweight lens that was recently improved significantly, with revised optics and the addition of optical vibration reduction (VR, like Canon's IS) that offers you about a two-stop advantage in low light. That means that a picture that would have required a shutter speed of, say 1/200 second on this old lens can generally be taken at about 1/50th of a second on the new version. (Unless your subject itself is moving.) The result is that you can use lower ISO settings for equivalent results or, at maximum ISO, get sharp pictures that you otherwise wouldn't have been able to manage. Look for the version that includes VR in its name - today (26 Sept 2007) it's retailing in many places, including Amazon UK sellers, for less than this older one. See Thom Hogan's pages - bythom.com - for more detail and a comparison between the two lenses. The new one justifies one extra star for its performance.