As a long time lurker and recent active poster I continue to be shocked by the thrashing, whining and crying here regarding the real and imagined limitations of the 5D Mark III. If you read Nikon Rumors ( you should it is very informative and professional) nothing like that happened there with their two recent introductions and there were almost no catty attacks at Canon as you find regularly against Nikon and any firm that doesn't worship Canon properly or at the same time knock it down appropriately.
What I find most interesting is the crappy quality of 90% of the photos that these anxious obsessives have posted here to get feedback. I'm talking about crappy composition, worthless lighting, impossible focusing situations, horrible white balance and basically most norms of decent photography violated in the service of complaining, worrying or hand wringing. Much of this was just impulsive childish behavior - pure and simple. When you can't tell the trolls from the faithful things have gotten out of hand.
That all said, of course there are issues and the camera, as amazing as it is, did not meet all the expectations and there have been some surprises. How could it? There were compromises made along the way - ie. 22 vs 36 Megapixels - there would have been complaints either way. You can just make a list but from where I sit it is was mainly cup half empty or half full. I have played with two copies and I would love to have one!
I wonder what the reception would have been if it was priced $1,000 cheaper? Would it have been received with less anger and skepticism. Don't get me wrong. It is all not emotional but, I'm afraid, much of what is written here sounds like what a grammar school child that is waiting and waiting and waiting for a beanie baby would write. It could never meet all the needs once it was shipped from Amazon. Was the packing enough for my beanie baby? Should I have waited for another color? What is coming out next?
There is a lot of very worth while information also available here from very knowledgeable shooters but the nut cases and the unstable one are winning out. I have learned a great deal about Canon products and photography in general reading here. That is why I lurked and will lurk.
In closing....if your blood pressure has risen since the introduction and you are hitting refresh every few minutes, take a chill pill, learn basic photography first, read the friggin' manual, do the necessary adjustments to the camera and its settings ( don't be a d0uche!) and finally take some decent shots that you can share for feedback and assistance. Most importantly buy from a retailer that will calmly accept your return. That is a sane option if this camera is ruining your life and, of course, there will always be Nikon.
I find early adopters without the proper risk taking temperament are the root cause of most the problems here. Canon's product has become secondary. Thank god the introduction of the flagship model will cost almost what a car costs. The angst will mainly be virtual.