I just aquired my 70-200 2.8 IS MK II in a trade for the Mk I this week. After some test shots around the house, I can say that I'm pleased with the results. This lens is expensive for sure and some will turn away at the price premium($2500.00 USD) and get the MK I. The MK I version of this lens is still a great value and will continue to hold it's value for some time. Is it worth it to me? I think so. The IQ mated to the current flagship 1Ds MK III makes it worth the extra donuts.
My testing in the images below is done handheld. No tripods were used during this test. The reason for my testing is to see how much I can push the 4 stop IS w/o blur. I was able to shoot this lens at 1/15 sec at ISO 3200 w/o getting blur. Honestly, I would never shoot this SS unless I needed to but, the subject has to be static.
Here are the pics.
1) EXIF: 2.8,165mm, ISO 200, SS 1/250.
2)EXIF: f/4, 120mm, ISO 500, SS 1/80.
3) EXIF: 6.3, 200mm, ISO 640, SS 1/60.
4)2.8, 70mm, ISO 400, SS 1/160.
5)f/5, 105mm, ISO 400, SS 1/30.