They brought it out because it was spec'd exactly the way I wanted it....and I could not wait any longer 
Would I have liked a better price? Yes....but a few hundred USD are not a major issue, and I blame that more on the weak $, not, so much, Canon.
Greater DR at low ISO? Maybe..? But more as insurance against my not getting the correct exposure. While intellectually it may seem nice to open up all the dark shadows, an image like that usually looks too artificial and is why we often tire of HDR....even if it is not garish.
More megapixels? Always nice, but has trade offs....which I guess is true of pretty much all the specs. It's like what we are told about tripods....if you want cheap, light, and sturdy, you can have any 2, but not all three.
In summary,I believe the 5D3 is an extremely well balanced system....and aim glad I jump on getting it right away (even if it is going to need some taping up).
John
The DR is VERY BAD on this body! What do you mean a maybe? Have you even seen how it compares to, say D800? It is like comparing a Fiat to a nice BMW when it comes to DR! The IQ across all kinds of situations is evident by the sensor!
If you are going to spend $3500 at least spend it on a worth-while body! Otherwise, stick with $500 cameras capable of raw - you will get the same IQ as the Canon 5D MKIII when it comes to noise, and DR.
It is beyond pathetic how some people can find reasons to justify their purchase! It is a bad purchase at that price! Something like that should have been priced at $2500, and they should have reduced the cost of 5D MKII to about $1800 - but they got greedy! Hiked the price of MKII by about $300 here in Canada!
I am not a stupid customer and will not budge just because they have a new body! Screw them! I am going to wait until the price for the quality is worthwhile. I am happy with my 40D which has better IQ than the 50D and 60D with the lenses I have!