The Panasonic P50UP50 should have been called "PU" because it stinks. I loved having 50" of screen real estate, but after a month of watching and configuring it, even my wife (who normally doesn't complain about sound or picture quality issues) said the washed-out look of this set was driving her crazy. After adjusting this Panasonic plasma set by eye wouldn't satisfy me or my family, I attempted calibrating using the THX Optimizer test patterns. Nothing I tried would bring this TV up to the levels of brightness and contrast of my previous set. It had excellent black levels and normal white (or "hot") areas of the screen would like fine, but as soon as the screen needed to be bright, the set failed to bring out the levels of white I expected. To illustrate the point, a movie or a TV show would look fine, but anytime the scene called for an all-white background, it would be dull.
I found that the dullness of the white areas depended on other on-screen content. For example, if you're seeing an all-white scene (say, a snow scene), white would be dull. But as soon as I pulled up the TV's menu system (which blocks about two-thirds of the screen), the remaining one-third (white) area would brighten to expected levels. If I closed the menu, the screen would fill with dull white again. It acted as if the TV was simply incapable of producing brilliant white if needed across the whole screen but could do so just fine if white is confined to a smaller space. I turned off every automatic processing feature I could access but could not reduce this effect. I had contrast up to 100% (which is the main control for enhancing the power of "white") and had brightness up to 80% (which is the main control for enhancing the lightness of shadows).
I replaced this set with 46" LED by Samsung. While I do miss the Panasonic's 50" screen, and there is a slight issue with not having as wide a viewing angle as plasma, I finally have the brightness my family and I have come to expect in our living room. I don't have a bright living room either, but even with the lights completely off, the plasma set still couldn't produce the full-screen white levels I knew it should. I've also completely negated the LED's motion blur and soap opera effects by manually adjusting blur and judder to my liking. Samsung offers granular controls over the entire viewing experience. So, while I cannot recommend this Panasonic set to anyone, I can whole-heartedly recommend the Samsung 46" 1080p LED Model Samsung UN46EH6000 46-Inch 1080p 240 Hz LED HDTV.