Interesting how experiences can vary. I sent the 5diii back with the feeling that there was no real life difference over my 5dii. After reviewing the results from an event I shot with both cameras I had no desire to upgrade at all.
Yes, the focus of course is faster. But especially having all these extra AF points in the same confined area around the center provided no benefit in my book. If anything it slowed emu down having to scroll through too many of them.
I'd like to see fewer AF points but further spread out across the screen.
But then again I have a feeling that future models will have even more "features" that I have no use for.
Yes, they will, and perhaps include sensors so overloaded with pixels as to be of little practical use for most people. And I agree with you about AF points. I added a 6D to my 5DII for the better image quality and then replaced my 5DII with a 5DIII mainly to be better able to avoid focus/recompose and there seems little doubt that, as dslr focusing experiences go, the 5DIII/1Dx are still the best (better, anyway, than the Nikon equivalents in my limited - rental - experience). But the focus points still take up a small portion of the screen. I've also bought an Olympus OM-D, whose focus points are almost edge-to-edge and which focuses very fast and accurately and, as I have little interest in photographing things that move, must say that from that point of view it beats any dslr I've used. (Such coverage may require the camera to be mirrorless, but it's obviously the case that not all mirrorless cameras are good at it; I've recently been trying a Fuji X-e1 which has worse coverage and shockingly inaccurate autofocus - except for fairly large things close-up I've given up and resorted to manual focusing instead.)
As for the two lenses, I'm sure the new 24-70 is sharper, and for all I know it does windows too. It's not for me, though, and I don't think it would be if it were half the price. Perhaps I'm weird, but I find the range limiting at both ends, prefer to have IS and while there are obviously types of photography where maximum sharpness is important, I seldom take photos myself where minor differences in sharpness matter (sure, I often look at photos I've taken with some lenses and say to myself "wow, that's sharp", but the nagging question "so what?" is never that far away). Maybe I have an unusually good copy of the 24-105, but on all three FF Canons I've owned the images it makes are sharp enough that I'm disinclined to complain and I've had no problems at all with either speed or accuracy focusing in very low light; even though I have much faster lenses, and even though it's certainly not my favorite lens, it's probably my go-to lens for wandering around town at night - like the Energizer Bunny it just works....