Ron,
I have had mine for 6 months, my dad has had one for three years. They do generate heat but I really don't feel they draw excessive power, nor do I feel they run that much hotter than a tube TV. I have never heard the cooling fans turn on, but I don't have them tightly enclosed either.
Most Plasmas are guaranteed to 20-60,000 hours, do the math for your typical viewing time, you'll be wanting one of those Lasar TV's by then
But to answer your question, I really haven't noticed any degradation in picture quality. But, we are not extreme TV-aholics either.
Joe,
Plasmas have a great viewing angle and there is no negative picture from any angle, one of the reasons I got it.
the Plasma vs. LCD wars are as passionate and Ford vs. _________ (insert other auto maker here)
I could list the specific pro-cons for either, but I don't feel like spending the time today. Look at the links I posted.
one thing I will add, the profit margin is better on LCD's/DLP's than Plasmas which is why most retailers will push those and perpetuate unreasonable downplay of plasma models.