I would concur to the IQ being similar, slight improvement over 5D2, at least at the lower ISO settings. At higher ISO the 5D3 does have less noise making the usefulness of the body that much greater. Colour, contrast, sharpness are an improvement. With 7D I had to raise sharpness in the body, the 5D2 I left it alone, with the 5D3 I have turned it down in the body. There is such a thing as too much detail of minor blemishes in portrait type work.

Have found with f2.8 lenses that there is no issue with focusing in very low light (lights off in the room at night taking shots into the closet to see if it would do it). Suspect that any long focus times may be from using larger aperture lenses. Believe that Neuro shed some light earlier on the difference in how the focus system functions beyond the f2.8 barrier.

I do find that the improvements in JPEG images is making a difference for me, especially for indoor events. When I cover larger events and am taking 1000+ shots a day, I don't shoot in RAW because I don't want the post-processing work. Being able to jack up the ISO with confidence in the results is still very novel to me, and it will likely take some time for that to wear off.

Being a two body shooter at events, there will definitely be another 5D3 in my near future. Have already sold my 7D bodies and am down to one 5D2 which I will be using as my walk-around and with my 17-40 for landscapes.