Mine actually was delivered tonight by UPS a day early. Thats the first time in many years they have delivered early. (I knew it was going to arrive, because I'd been following the tracking)
It was 6:15 pm and overcast, and pretty dark. I turned out the lights, but, no, it does not focus or take images in the dark with my 24-105mm L.
I went into my warehouse back room, which was barely lit from the windows with lights out and snapped a shot at ISO 12800. (manual with auto ISO). There was backlighting thru the window, it did not look like it, but in the photo I can see the exposure was pushed to the left.
Still, I was suprised. I'll be trying the camera out tomorrow, I'm still installing software and getting ready.
The camera can be used at 12800 with reasonably careful exposures, but at 25600, expose to the right a little. Very little DR at that high ISO.
I tried a little NR and it cleaned up nicely. There is some color nr turned on, but no luminance or sharpening. I used Adobe DNG converter, not DPP.