I used it on the 7D, and it was a very good lens. Comes down to whether the focal length range suits you. I rarely shoot wide, so it was a good fit. Also, it allows you to shoot fairly close which is handy for stock. In the end, though, I used a macro over the zoom for stock work. Zooms tend to be optically inferior to a good prime stopped down a bit.
It depends a bit on your photographic style, the faster lens f2.8, might help blur a little more the background, but for me IS is more important, I want a bit more of DOF normally, not a portrait photographer.
I had one 24-70 for an afternoon and didnt like it.
One thing I didnt like at all on the 24-70 is the size of the "jumbo" lens hood, its huge and ackward to use, I need something more practical at my trips even though obviously it protects better from the sun, but it was very complicated to put my camera back on the bag with that huge thing and to switch it to the front, I just lost a lot of agility with that lens. Besides that, I noticed I had to change the lens quite more often, needing more my 70-300 telephoto lens, which is not an L grade lens, so I was loosing quality between 70 to 105 mm.
Qualitywise comparing images in the same range (24-70 f4.0 and up), they are not much diferent one from each other, the 24-105 is a bit more prone to vigneting, so you need a very narrow filter, the 24-70 has no problem with that.
And the fact that the 24-105 has IS allows me to take a lot of images with a smaller aperture, handheld, that for me was the break dealer (and it was much cheaper too...)
But thats a very personal decision, you might want f2.8 to blur the background for some reason, even though at 105mm and f4, and a close subject the background blurrs a lot as well.
My profile image is me holding the 5D with the 24-105, BTW.
Great all round lens, had one for years and never had a problem, consistently returns quality results, used mine in the studio and outdoors and haven't experienced any of the issues described above. This is Canons flagship lens and the reason the top Canon speedlites have a zoom between 24-105.
Elinchrom and Bowens studio lights, Gitzo tripod and geared head, Pho...