I still have one that carried over from my film days that i play around with. The lens is/was a good performing lens Optics wise, zoom speed* and subtle focus change is moderatly fast. Bad part is slow on inital focus, noisy its, not smooth feeling. Remember this is Canons first ventures into the telephoto lens.
I'll be honest here the lens isnt light compared to modern ones, but it is rugged and holds its own for performace of the glass. zooming out is a breeze with the sliding Body type but she aint so great in the weight or speedy AF. Macro is pretty good but isnt something i would do with it regularly, thats what i have the Sigma 105.
hope this helps.
Sam