A great lens, a very good quality. What to say but that I didn't regret going from canon to sigma concerning the lenses. I just love sigma lenses.
When you do pictures in hostile environments like me in the air when you run through clouds or dust clouds and even rain i can assure you that sigma is more robust than those xhite lenses from canon. More than a pair of white 70-200 broke while taking air to air pictures in difficult conditions.