reality
I was recently in a camera shop and they let my mount a 70-200 2.8 IS II on my 5DmkI.
I took a head shot of my wife handheld at ISO 3200, 20mm, f2.8, 1/250. On the 5D ISO 3200 is pretty noisy but I was very impressed with this lens. She was tack sharp and the background was very nicely blurred. If I had the $$’s, I would not hesitate to purchase this lens. All the comments I have heard about this lens complained about how heavy it is. Mounted on my 5D with battery grip I feel I could carry this around for hours. It was very nicely balanced. Since I did not have the $$’s, I purchased the 50mm f1.4 instead. I have never used the 85mm.
Mark