So I just got the 24 - 105 to replace my EF-S 18-135.
First time dealing with RytherCamera, and despite the hard push on accessories when I needed to upgrade my shipping, overall arrived fine... White Box special which I would have preferred to know about up front, but New is New and at $900, not too bad
I still have not learned how to "test" a lens, but gave it a 5 minute look over, all elements look clean, AF seems quick and accurate, nothing seems loose....
The only one thing that concerns me is the zoom feels firm. It is not tight, but compared to my 70-200 F4L Non-IS just seems like there is a small degree more needed to turn the ring, and there is a tiny bid more sound when turning the ring compared to the 70-200. Have a full warranty from Canon, but looking to more experienced folks as to if this is normal, a "feature" of the lens, or a sign of slightly poorer build that should be sent in for servicing.