It's time to emphasize one clear point about the F8500...it offers the best picture quality of any tv...ever, at least at this moment in time. The only other tv that may rival it this year is the ZT60, it's the only other tv offering a unique panel design that may rival Samsung's super contrast panel. If removing the air layer from the plasma panel, as Panasonic has done with the ZT60, will result in as good, or an even better picture than the F8500 is unknown. The only information we have on that is from CES 2013 and I have not seen a single individual make a comparison between them, but...other than futuristic panels, the F8500 was the star of that show.
It's good to try to determine what issues the F8500 may have, but it's important not minimize the fact that it provides clarity and detail you have never seen before...a truly spectacular picture. Considering plasma picture quality has been pretty much stagnant for almost 10 years now, that's an incredibly wonderful feature : )