I got it second hand from a close friends. Pretty happy with it so far. I've been wanting this lens for quite some time since I couldn't afford a 16-35L and didn't want to get the 10-22 also.
So far, no problems with it. My copy is pretty sharp. Printed some 12x18"s and am very satisfied with the results that this lens gave.
It's a perfect lens for indoors and landscapes. I've yet to use it for portraiture.