This is nearly a perfect lens. There are countless reviews on this lens that go into much greater detail than I could ever say so I'll keep it brief. First off this is not the IS version, but optically they should be the same.
A decent sized zoom with a constant f/2.8 is very handy when you need it. It works well for portraits if you're shooting outside, or have a very large studio. The bokeh is also creamy smooth like some of the other "L" lenses. I regret selling this one. I was going through an "everything must be a prime" stage and sold it off to fund the 135L. Now I wish I could have it back.
I wouldn't have any regrets recommending this lens to anyone. It works well for sports, portraits, isolated landscapes, product photography, etc...
The photos below were taken with a 20D.
105mm, 1/800th @ f/2.8, ISO400
70mm, 1/400th @ f/8, ISO400
70mm, 1/800th @ f/2.8, ISO400
70mm, 1/1250th @ f/2.8, ISO800
70mm, 1/320th @ f/6.3, ISO200
105mm, 1/250th @ f/8, ISO100
***this image was taken with extension tubes mounted to give you a pseudo macro effect**
160mm, 1/100th @ f/9, ISO100
***extension tubes used here too***
(Mods, if this portion belongs in another thread please feel free to move it. Thanks)
Since there are a few product shots posted here I thought I'd mention a few helpful pointers when shooting stock or product photography.
1. Shoot at the lowest possible ISO
2. Shoot at a high f-stop if you are trying to capture detail or increase the dof.
3. A tripod and remote release is a must. I guess self timer may work too.
4. Use multiple lighting sources to avoid shadows as much as possible.
5. Try to isolate your subject as much as possible.