I don't have any test shots to post at the moment (they are still on the camera) but I had a brief play with my 5DMkIII last night and what I can say unequivocally is that I was obtaining low light shots that would have been impossible with my 1DMkII without flash - and that was in intelligent auto mode with max ISO 12,800. The quality of the images on the back of the camera blew me away. Admittedly I didn't do any 'pixel peeping' but like I say, compared with my 1DMkII, well ... there's just no comparison! The only slight advantage I can see to the 1DMkII is the shooting speed, although at roughly 8 fps versus 6 fps even that doesn't seem to be such a huge difference on paper. I think the 5DMkIII will suit my needs very well for the forseeable future
Oh, and (much to my relief) the autofocus is astonishingly accurate right out of the box. With the 24-105 kit lens and absolutely NO micro adjustment, it was nailing focus spot on in semi darkness. Really happy with this ... particularly given that I've recently had to send my 1DMkII and a couple of lenses off to a Canon repair centre for AF calibration (there's no micro adjustment facility on the 1DMkII).
Of course, comparing with the 1DMkII (relatively old technology now) there was bound to be a sea change in IQ, which is why I'd be interested to know what 5DMkII users think of the MkIII when they have the opportunity to compare side by side (actual test shots).
