I saw the Sharp 80" at Best Buy Magnolia today, and was impressed. The picture is definitely an improvement over the Sharp 70". Viewing angle and evenness were better. It seemed like they fixed the problems of the 70". It is just big enough to get that immersive movie" experience that you just can't quite get with a 65" TV no matter how close you sit.
I did see the graininess people were describing, and no it it not because you are too close, although certainly the closer you are the more you see it. Certain types of material seem to "set it off". I did not see the same issue with similar material on a nearby Panasonic plasma 65" VT30. I think there is a quirk in the video processing. It is not there all the time.
The picture is not as natural as the Panny VT30, but still very good. I put the set in Film mode, and was pleasantly surprised that the colors were not all pumped up, giving everything a cartoon look, that you so often see on LCDs. It is one of the few LCDs that is enjoyable to watch.
I hear some people saying they are waiting for features such as Quattron. What for? It doesn't expand the color space any, and it just one more subpixel to get stuck or burn out. When I asked Sharp at CES what real benefit Quattron has, they couldn't give me one. I'm glad they didn't put Quattron on this set.