Summary: Key features I upgraded from Mark II for: 1. bracketing 3,5 or 7 images - fantastic for HDR 2. auto sensor cleaning - useless or broken. 3. 14-bit per channel - good improvement 4. 21.1mp - Challenges "L" glass. Surprises - bonuses Bigger LCD - Big improvement like much more than I thought. Button/Control layout - big improvement much more intuitive. Battery life is so good that you forget it exists. Have 2bats - I go on week long shoots without a charger.
Excerpt: The camera came new with two problems that should have been caught by proper QA/QC. Service of the camera has resulted in some problems not being fixed and new problems introduced. The automatic AF point selection (ring of fire mode) is basically useless. The camera's AF system will sometimes fail to achieve proper focus resulting in soft focus images.
Summary: As a professional specializing in fine art catalogues and interiors, this camera is a useful addition to my kit (already have an MFDB). Files are extremely fine, if a bit flat. They need a lot of work in ACR. However, my big crib is that mine came with the dreaded mis-aligned viewfinder. Since everything I do involves either squaring off or horizontal/vertical alignment, this is a serious manufacturing error. And I am not alone. Many others have the same problem.
Summary: I have shot about 2,000 pics with this camera and have some preliminary thoughts.All in all I was expecting something significantly better or upgrade to my 1ds mkII ; it is not.The only real improvement I see is the live screen . ,no perceptible change in image despite 25% increase in pixel count (30 x 40 inch size).Furthermore , it also is disappointing at ISO 1600 and above.I will probably return it and look seriously at the new Nikon D3.