Summary: Let's be honest... a "kit lens" that adds approximately $70 to the overall price of a camera body is not supposed to be Canon L-series quality. Sure, you can find a better quality lens, but not for $70 you can't! I plan to use this lens as a knock around lens that allows me to get more familiar with my camera and run off some shots.
Summary: I am a portrait professional photographer for over 40 years. I needed a wide angle lens for weddings and wanted to know the quality of the kit lens. I did a test using the Rebel XT kit lens and a Canon 16-35mm lens which costs somewhere around $1,500. I set both cameras at 18mm focal length on a tripod. I took shots outdoors and indoors. The images were done exactly the same. The outdoor shots show objects at infinity as well as 10' away.
Summary: As mentioned before, it is important to realize that this lens is NOT the kit lens that Canon includes with its digital SLR cameras. It has an ultrasonic motor (USM), which is the reason I bought my Rebel XT's body without a lens and picked up this lens to go with it. The USM feature means the focus is very quick, accurate, and nearly silent compared to many other lenses.
Summary: A good lens for outdoor use. A bit too slow for indoor use, though. I got this to replace the kit lens that came with my Rebel XTi. The kit lens was okay, but I wanted a lens with like quality to my camera. I probabaly really don't need it as I have the 28-135mm IS USM, but I got the 18-55mm first. At least it's a good backup lens.