9 out of 10 points and recommendedEase of use, image quality, OS, buildLack of full-time focus, lack of hyperfocal markings
Had to choose between Canon 17-55 and this Sigma. Tried both, and very happy with the Sigma. Image quality is superb, as good as an L-lens I borrowed for a while. Manual focus is tricky, with a short turn (30 degrees?) and distance scale is therefore cramped, making hyperfocal settings tricky - I do a lot of landscape and outdoor work. Working round lack of full-time manual focus is a little annoying, but I got used to it fairly quickly. Switches for OS and Auto/Man focus work well, as does the zoom lock, just in the right place.reviewed August 7th, 2011 (purchased for $930)
Overall, very satisfied with this Sigma 17-50. Excellent choice as replacement for standard kit lens, as well as Canon 17-85. Slightly better in my opinion than the Canon 15-85.
Had to return the lens direct to Sigma for autofocus problems, but returned to me in one week, focus fixed, lens better than ever.