I've got the G6 since 3 weeks now and generally i agree with Andrew's review. But there is not only light, there is also shadow.
1) I've noticed a dramatic difference between the 25/24p (30/24p) mode and the 50p mode. The 50p mode is less sharp and detailed. Absolutely visible.
25p (Natural) 100%
Comparing the full screen shots side by side one can see that the 50p image seems to be stretched somehow. This might be the reason for negative reviews of some magazines here in Germany. I guess they made their tests in 50p (Can't tell you 60p mode has got the same problem).
2) The difference between the GH2 footage and the G6 footage is minor, but visible. The GH2 stills wins (under good lighting conditions). But not easy to see when played back on a LCD TV. However at low light the G6 shows less grain. ISO1600 is very clean (comparable to ISO800 at the GH2). From ISO3200 the image is less sharp (compared to ISO1600).
And here another low-light comparison between the GH2 and the G6
GH2 at 3.5, 1/50s (24p, at 25p footage is slightly less grainy)
G6 at 3.5, 1/50s, 25p
3) The preview on the LCD is not always what you see after pressing the record button. The color shift is sometimes more dramatic than it was on the GH2. Also the preview at low light in EX-Tele mode is grainy. After pressing record it is not. It's not easy to judge the image before recording. It is looking like a RAW preview :)