I love mine to death, but it did give me a scare after about two months of use. I had my IS on during a shoot, dipped my camera down, and then heard a terrible grinding noise. Literally scared the crap out of me. I've had it for almost 8 months and it's still working fine, but if I happen to move the lens up or down while the IS is on, it sounds like metal on metal for a second or two. I would have sent it off to Canon to get it checked out, but I've heard too many horror stories about lenses being sent to Canon and never working the same way after a repair. The sharpness and contrast is unreal, and I'd rather deal with a little grinding and having the IS crap out on me after 2 years as BozillaNZ said than take a chance of affecting the quality it's currently putting out.