OK, I did not have the patience to read the responses to this decidedly inflammatory post but that wont stop me from leaping in with my .02
I too, thought that the price was high for what seemed a subtle makeover of the mk2. However, I found myself in the position of getting a large number of jobs that required snappy low light AF and preferably a silent camera. The mk3 became increasingly interesting to me because the AF is such a large improvement over the mk2.
I am a full time pro so it was just business. I ordered one and it came in a few days ago. After using it bit I realized it is dramatically different and better than my mk2s.
The AF is snappy, the locking mode dial is perfect, the customization options are huge and the general build, fit and handling are significantly better.
I then read a review by Ellis Vener who noted that it should really be thought of as replacement for the 1DsMk3. I agree completely.
It is as if Canon listened to all the whiners who said " I love the mk2 but I want weather sealing, dual card slots, better AF, more customization, built-in HDR, better video, and I want it for half the price."
Voila, the mk3. I am delighted that it reminds me of my 1Dmk2 in responsiveness yet weighs a lot less. Frame rates are not a huge deal to me but this camera still can do sports if you have the skills of the old time pros that actually anticipated the action.
At bottom the haters miss the point. Canon gave them the 1DSmk4 without the weight and at half the price.