Significant variation between the two lenses Bryan tested, especially in the center at 70 mm. I guess that is something to watch out for. But, everything I am seeing shows that this lens is an optical beast.

Here is the second copy of Bryan's test against the 70-200 II @ 70 mm:

http://www.the-digital-picture.com/R...mp=0&APIComp=0

Contrary to Rogers tests at lensrentals, I'd still give sharpness to the 70-200 II. But, for example, someone on CR is considering dropping a 35 mm L for the new 24-70. Here is that comparison at f/2.8:

Bryan's second copy:

http://www.the-digital-picture.com/R...mp=0&APIComp=3

Even better, Bryan's first copy:
http://www.the-digital-picture.com/R...mp=0&APIComp=3

Call me impressed.