When the 5Dmk3 first came out I too was one of the doubters about the value of the camera. I had a 5Dmk2 and I picked up an additional one for half the price of the mk3.
What convinced me to get the mk3 was the silent shooting mode and the AF. Both these features are enormously helpful for my work.
Silent shooting is hugely underrated. Not only do you get near-Leica levels of quiet but also near-Leica levels of feel with the shutter release. The build is excellent and the images out of it are superb.
Yes, I do still have a mk2 but I think I will be trading it in on a mk3.
Amen! It is the best camera I've ever had.
5D MK III, 16-35/2.8 L II, 24-70/2.8 VC, 24-105/4 L IS, 70-200/2.8 L IS II, 100/2.8 L IS, 40/2.8, 50/1.4, 85/1.8, 150-500 OS, 600EX-RTx2, ST-E3-RT, Rokinon 24/3.5 T-S, D7100+18-300 VR, YN568EX, 055CXPRO4+468MGRC2, 190CXPRO4+322RC2, Gorillapod Focus+496RC2, CamRanger, B+W filters, Konova K3/31.5 etc