The heat! Many plasma displays had a faint heat you would feel on your face if you were near that I found uncomfortable. I am not sure if others felt the same.
I had a year of sickness, or so, back in the day. I decided I was gonna blow as much money as I could on the "best" TV setup. I bought a 42" plasma TV, and I sat it on the floor in my living room, in front of a window.
You could see the heat-haze above the screen, the air shimmering in front of the window, after it had been on for a while.
Lovely display, far too expensive, and far far too heavy, but for the five+ years I kept it I think I got my money's worth.
