Got this in combo with a 20D for a really cheap price, thinking it'd be just a little better than the kit lens for Canon. Well, I'm pleasantly surprised, it's not very sharp wide open, but stopped down to f/4 or f/5.6 it holds up quite well. The macro is closer than the more recent versions of the lens, and it's useful for anything but small bugs. Auto-focus isnt super fast, but, I shoot plenty of action with it and haven't been missing shots.
The barrel distortion is pretty comical at 17mm, seeing Photoshop correct it is always a bit mind-bending. But it seems to go away by 24mm or so. The exterior of the lens is actually pretty nice, but zooming and focusing makes the lens feel a little cheap and plastic-y.
Still, for a low price, it's much more versatile than the average kit lens and it makes a great walk-around lens.