Got this lens about 4 years ago. First used it on a 450d. Initial impressions was that this lens had very nice and accurate color rendition, especially on standard mode on the 450d. A problem which occurred was that every picture taken at f8-f11 was blurry and out of focus. Sent for calibration.
It came back from calibration as another lens! Fast and silent auto focus, mostly accurate. I used it for the bulk of my shooting on the 450d and it matches up very well with the EF-S 10-22mm lens as a 2 lens travel kit. Pictures are nice and reasonably sharp (takes mild sharpening in post). Very nice colors. Good contrast. Bokeh acceptable, especially if taking the fact that this is a f4 lens and a very wide range zoom. IS helps for lowish light. I have used it for documenting company events with an external flash and results are generally acceptable for what it does. The only bad point is barrel distortion which thankfully is easily correctable in post-processing with the provided canon software.
Am using it now on a 5d2. Finding absolutely no reason that I would ever need to get rid of it. A basic, does a lot, does it well (without ever being spectacular) lens.