Plasma TVs are pretty cool in my opinion. They’re relatively reasonably priced, even for larger screen sizes. However they are power hogs relative to LCDs and they are consumables, in the sense that brightess decreases the more you use them.
In fact, they have a half-life, in the sense that the brightess decreases by 50% over a certain number of viewing hours. But the half-life is pretty long – manufacturers generally claim 30,000 – 60,000 hours. That means that assuming 5 hours of viewing per day, every day, it would take between 16 and 32 years to reach half brightness.
A purist might argue that the brightness starts fading straight away, but I’m of the opinion that this is nonsense for all practical purposes. You’ll probably be able to notice a quarter less brightness but it won’t be a huge deal. And by the time you hit half brightness, you will probably have replaced the screen anyway.
One very important point though is that you should be very wary of second hand or ex-display screens. If you run a screen like this 24 hours/day instead of 5 hours/day, you find the half-life dropping to a range of 3.4 – 6.8 years on the basis of the same figures. You will find very cheap ex-display screens available, but be sure you know what you’re buying if you get one of these or you’re likely to be disappointed