Allister Freeman is a photographer who recently switched from Canon to Nikon. In this post on his blog (Canon 5D Mark 2 versus Nikon D700 – My thoughts), he tries to give a hands-on experience report to support his switch.
Actually, the most important of his issues was with ISO sensitivity and general behavior of the Canon EOS 5D MkII in low light (including digital noise and AF). Despite that the Canon is still a very strong seller, the reduced sensor resolution of the Nikon D700 has been superbly exploited to provide maximum sensitivity and minimum noise. I cannot help but agree with Allister.
A visit to his post will also show a nice set of pictures made during a wedding in the Gosfield Hall in Essex (England) and showing his excellent documentary style.