I was looking for a shorter zoom with IQ comparable to my 70-200 L f/4, which set the benchmark for image quality, sharpness and contrast for me. The 24-70 became my choice, taking the f/2.8 into consideration over the 24-105.
Being suspicious about the individual lens quality based on so many user reports in this and other forums, I did the “newspaper on the wall sharpness test” in the shop. Out of seven copies, five were useless, no center sharpness at all, the edges naturally being worse. So I picked one of the two remaining copies.
When looking at the real life pictures taken with the one I bought, I was less than impressed with the results. Missing the IQ and contrast I was looking for, I went straight to the Canon service center in Jakarta. They let me pick and try a new one and swapped it without any problem.
This one is fantastic, sharp and crisp pictures, nice contrast, true “L” quality. I love it!
My recommendation to fellow photographers is to buy the lens in a shop you trust and where you can be sure that they would replace your lens in case you got a bad copy (and such judgement can only be made by yourself). My recommendation to Canon: Do something about this issue, this is a “L” lens and an unnecessary quality assurance problem.