Also, LCD and LED panels suffer from something called judder. When something moves quickly across the screen you'll notice it doesn't move smoothly but it's almost like a sequence of photos and stutters across the screen. The plasmas don't suffer from this anything like as much.
LCDs are getting better at this though, when I was looking the top of the range sonys didn't suffer from it much (Z4500 and Z5500 i think)
Motion judder. The thing is until you have plasma you can't appreciate the qualities of it.