I know the spec's show the ISO range the same as the 5D III, but I think I am going to reserve judgment on this until I see some real results... I guess I am in "trust but verify" mode on this one. I would not think it would be wise for Canon to put out a spec for an ISO range that produced garbage at the high end (especially when they have proven capability with the 5D III and 1D X), but I think I would rather make them prove it rather than trust them. Unless I missed something, which is totally possible, I have not seen any results of their new sensor.
If the results are not as good as the 5D III, then I may opt to spend the extra $600 for the 5D III (based on the recent low cost offered on e-bay by Adorama).