canon

I use the 70-300 with a Digital Rebel, giving a maxium equivalent focal length of a 480mm lens on a 35mm film camera body. I thought about buying one of Canon's 70-200L series, but they are huge, white, and heavy. I am not a professional photographer and decided I didn't want to look like a geek trying to masquerade as one. Besides, I like to take my camera with me, like tucked under my ski jacket, so there is an upper limit to practicality.
So far, photos have mainly been of kids playing baseball. I've shot roughly 1000 pictures in the few weeks I've had it. From the outfield fence, I've been able to take some great pictures of the batters. At maximum focal length, tracking movement of players takes some skill, which I am still trying to master. From the baselines, I have to zoom out to keep the action in the frame. I haven't had a need yet to use the IS since I use a fast shutter speed for sports.
Picture quality is very good. Photos are crisp across the field. I assume the magazines will test this lens eventually under lab conditions, but I can't see any imperfections with real world photos.
My only complaint is with the zoom control. The lens has a lock to hold it in the shortest focal length because the lens will move by itself when pointed up or down. The rotating ring for the zoom control is a little too hard to rotate when the camera is level, and especially when going against gravity. It is fine for still subjects, but it is a challenge for quick focal length changes with sports. Gearing for a more rotation with less force would have made this lens ideal.