This lens preceded the 28-70/2.8L and 24-70/2.8L lenses, which are very
popular nowadays. This lens, however, never became nearly as popular, and
it was manufactured quite short a time. It has its quirks, but optically
it is rather good. Probably not as good as the newer substitutes, but good
enough.
Physically it's rather large and heavy, but I have gotten used to it. It's little larger than it's younger brothers 28-70L and 24-70L and a little heavier than the 28-70L, but lighter than the 24-70L.
It has it's quirks though: it's a fly-by-wire lens, so the manual focusing ring doesn't affect the lenses directly, but instead it controls the motor that moves the lenses. So no focusing without power. I mostly use the AF anyway, so haven't been bothered. I haven't noticed that the lens would be a batteryhog as some people have complained. I guess the 10D draws that much power anyway, that it isn't significant. The lens has an USM motor, so the AF is quite good. No fulltime manual focusing here.
Also the front lens rotates when focusing. Or actually there's a plastic ring in front of the lens, which you can hold with your hand when focusing, if you want to keep it still. Odd huh?
As I don't have a macro lens, I use my el cheapo Jessops extension tubes (but hey, set of three cost less than a single canon extension tube) with the lens, whenever I want to take macro shots. Works quite well.
Focal length: 64mm f/4.0