I've got one personally, as Aytex said, and I love it. It's probably the best laid-out camera I've ever used, with separate dials for shutter speed and aperture, which is super awesome for everything. I've adapted mine to fit old Canon FD lenses, which work well; m4/3 is super cool because you pretty much adapt anything to it. Since it's a smaller sensor, the G7 isn't that great in low-light, but with a low enough aperture and shutter speed at around ISO 1600, it's pretty good, with little noise.
The 4k video is definitely the selling feature of this camera, as you said. Everything is super crisp and smooth with a high enough class SD card (I ran into some weird issues before I switched to a U3 card). Unfortunately, it doesn't have above 60fps recording, so slow motion is out of the question, which kind of sucks.
Overall, I love the camera; it's super light, with crazy long battery life (3 days in a row once!), easy lens adaption, and a 3.5mm mic jack for an external microphone.