4 out of 10 points and not recommendedGood distortion performanceoverall sharpness, unusable wide open at 10mm
Reading the other reviews I can't believe I have the same lens. While the performance of the lens from f/5.6 is OK, wide open and in particular at 10mm is terrible in the corners. Maybe I'm too demanding but for this price I can't be satisfied with the fact that for the common focal lenghts my kit lens is sharper at every aperture.reviewed May 28th, 2007 (purchased for $700)
I also own a 28-70mm f/2.8L, for the record. I have compared 10-22mm against the 16-35mm f/2.8L for the common focal lenghts, and what a difference!
Contrary to what the other tests state, my copy is sharper at 22mm than at 10mm. Since I bought the lens for the 10mm range, where I need a very sharp foreground, I can't use this lens with the aperture wider than f/5.6
My copy was tested by Canon and it was within spec. Email me if you want details (very dissapointing tests).
Bottom line is that if you are considering this lens (which obviously can be great), buy it from a place where you can return it and test the lens thoroughly before you decide to keep it.