Truely remarkable camera. Even compared to both Canon and Nikon's flagship models, it holds it own at 25000 and is reasonable at 51200. Started comparing it to 7d, and the 5km3 beats it by at least 2 and nearly 3 stops.
You know we are going to need new terms for ios like kios (k=1000) so 25kiso and 51kiso.
The only thing I absolutely hate about the Canon 5k Mark iii, and I really despite it, is that I don't have it yet.