This AM I shot a few images at ISO 6400 and 12800 - amazing! Some noise, of course, but easily managed in LR4.3. Again, very quick and accurate focus in very dim light. Noise and focus not quite up to my Canon 5D3 (as reasonably expected), but a really nice surprise given the sensor size and price difference.
Hoo boy, looks like I will enjoy this baby, used primarily for travel. Now to learn the buttons, dials, and menus - much changed from the GH2, ouch!