The codec is 8-bit 4:2:2 h.264 Quicktime .mov at a max bit rate of 150mbps. Arguably better than the GH4's internal 8-bit 4:2:0 h.264 Quicktime .mov at 100mbps.
I rented it a few months ago (before the LOG update), and it looked very good next to 4K footage from my GH4. And the ergonomics (except for the awful viewfinder) were better than any still/video hybrid.
With J-LOG, Dan Chung was able to produce a grade that looked like this.
Thinking seriously about buying one at $2995.