I bought this lens together with my first digital SLR (EOS 300D) and took around 500 pictures with it. Image quality was good to very good (sharpness and colors). However it is not HSM and the Sigma dual focus system is really not very user friendly : you have to pull the switch and then the focusing barrell too !
Altogether it is heavy and bulky for the range it offers and the 82mm filters are Expensive !
Reading other reviews I guess I was still lucky to get one that focused properly and was sharp.
I since traded it for a canon 17-40 L usm and am happy I did