9 out of 10 points and recommendedVery Sharp Images for a zoom lens, 4 Stop IS, Fast USM Focus, Great Focal Length RangeVignetting, Distortion at wide range
Pros:reviewed December 2nd, 2009 (purchased for $720)
-IS performance is fantastic, delivers 4 stop or even more image stabilization.
-Sharpness is among the best for a zoom lens, it is sharp almost all along the focal length and up to very edge of the image. It can easily resolve a 12MP sensor. Sharpness is very comparable to 17-55 f/2.8 and 10-22mm (in wide range)
-construction quality is the best in canon's EF-S line.
-USM focus is fast and silent
-Flare is well controlled
-Vignetting is the weakness of this lens, it is very high in 15mm an doesn't get that much better by stopping down
-Barrel distortion is easily visible at wide range
I think it is canon's best EF-S lens for outdoor and general purpose. Great upgrade for 17-85mm