There are very few photographers I look up to. There are a lot of great ones, but only a select few inspire me. One of those people is Jeff Ascough, one of Canon's explorers of light.
To me, he's the best wedding photographer in the world and has no interest in the 600EX-RT! I love that.
Jeff has obviously had a 5D Mark III in his hands, and has released his review of the camera.
So are there any negatives to owning this camera? Maybe just one. You will lose the ability to blame the camera for any shortcomings in your own photographic ability. The camera is what every Canon user has been waiting for and then some.