We have had them in since Monday and if im being honest, it's a cracking tv and a noticable improvement over last years G10.
The design is nice and suttle, the frame around the screen is slimmer over the G10, the pedestal is not as wide but it still does swivel, also overall the tv seems slimmer than the G10 and it's pretty much all gloss black with a faint conture line where the Panasonic name is. Now that's the design over and done with, now for the performance, i have to say it's very very good, the 600Hz sub field drive is much much better than the G10, everything seems to flow nice on screen when movement is made, when it come's to picture quality, there is a difference, we compared it against a 42" G10 that we have remaining in store and the colour is better on the G20 but when it comes to sharpness etc, there was little between the two. Now for sound, it does seem to perform again better than the G10 but remember the G20 is not the flagship, so do not expect too much in regards to sound but for what it does, it does a great job. The biggest improvement is the specification, it's THX certified now, has a ISF mode (basically you can fine tune Gamma etc in regards to picture for someone who wants a more professional picture calibration), Freeview HD, Freesat HD, Viera Cast, Wi-Fi Ready, USB-Record (allows user to add an external Hard Drive so you can record from the built in tv tuners) and a new SD XC card reader which also reads the normal SD HC cards too (this allows Jpeg / AVCHD / DivXHD playback).
It's a very comprehensive tv for the money and with a vast host of features too, if i had a choice between last years G10 or G15 at a cheap price or the new G20, i'd go for the new G20 in terms of what it offers as an overall package.
Regards> M