I have the 55" of the ST50 generation and have been really impressed with it. The ST line of Panasonic plasmas are an incredible value.
Just one tip that has been an issue with mine is image retention. I have a habit of watching Sportscenter and ESPN News as my default channels for background TV and occasionally falling asleep and leaving it on all night. I have noticed some bad image retention at times from the bottom bar that stays on even during commercials with ESPN News.