I replaced my 18-55mm Kit lens with this 17-85mm IS lens and think it's the best. I now keep the 17-85mm lens on the camera but am searching for the perfect telephoto lens. After about 1200 shots, it's still seeing pictures just as well as it was on day 1.
The build quality on this lens reminds me of a tank. It's rock-solid and I don't have to worry about it when I'm hauling it around in my bag. I can go from 17mm wide and zoom to 85mm in a snap. The motor is super quiet and focusing in quick.