A couple of months ago, I bought a new 5D MK II. I've only been able to play with it recently. The first time was about a week ago. I used it for about 3 hrs. with my 24-105. Initially, I didn't see any major issues. Images were a bit soft but not overly so. Then this past weekend, I had an opportunity to visit a flower farm located in the wine country of Amador county, CA. I originally only planned on visiting the place on Saturday, but I wasn't happy with the results I achieved (handheld) with my 100 2.8L IS Macro so the next day (Sunday), I went back - this time with a tripod. Long story short -- I could not get the camera/lens combo to focus. I mean it looked like I achieved focus but viewing the images later on my computer monitor elicited a WTF !!!
Maybe my eyes are going bad and I'm getting too old for this hobby but nothing and I mean not one image was sharply focused. When I first got the 100 2.8L IS Macro, I put it on my T3i and I was able to get some really nice handheld shots. Totally different experience with the 5D MK II.