There's at least one other long thread on this. The consensus was that most (myself included) who bought the 24-70 II subsequently sold their 24-105.
Yeah, but most of the other threads are about people not wanting to sell their 24-105 for the low price it is fetching. I was hoping for a little more input on IQ. Are people happy b/c they are getting better images? Is it noticeably sharper for those who print bigger? IQ discussion anyone?
If you can get a good copy of the lens it's much sharper, and the images will be much more contrasty. I, myself, had to get four copies of the lens to finally be satisfied, and even then this copy I have now is not perfect.
The one thing I will say for the 24–105mm is that it is a robust lens that has been around for a long time and has very few problems.
I do regret selling mine, only because I almost completely stopped taking pictures while my 24-70 mm was in for repair at Canon. Unfortunately I had to use the money from it to pay for the new lens.