All this negative commentary on the 5D Mk III has become a joke!

To clarify the 2-stop improvement claim at high ISO, this is my "real world" impression. All else being equal I was glad to shoot with the 5D Mk II to 1600 routinely and I will now shoot with the 5D Mk III at ISO 6400 without reservations. I do not get that worked up about noise, banding etc (same lenses). Again the subject, composition, lighting etc so out-way these technical considerations that they are trivial issues, if present at all, in most of the photos I take. More importantly, fast accurate focus especially in low light is a real step forward in my opinion (kudos to Canon on this one!).

A couple of points (I ALWAYS SHOOT RAW NEVER JPEG);

1. The focus accuracy being so much better means you get a greater number of images sharp at high ISO and the images are easier to work with in LR.

2. The quality of the noise seems easier to control in LR than with the 5D Mk II

Therefore, my impression is that there is a "real world" improvement of 2 stops (i.e. when out and about shooting pictures not examining test patterns).

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Nick