Before I bought a few 27" monitors I used to use my 50" LCD, it sounds really awesome when you first think of it, but in practice its not great.
If it's plasma, its bright enough, but the detail isn't too nice, and if it's LCD, its sharp enough, but not too bright, LED is a nice mix of the two, but overall, no TV screen (That I know of) has a resolution higher than 1080P which is 1920x1080, most 20" monitors and bigger have larger resolutions than this, so WoW is nice, but it looks horrible because everything is so large on the screen.
But it's all personal preferance, most people probably can't afford multiple monitors or large ones so it would be nice to use the TV, and don't get me wrong, its not the worst, I just don't find it great for gaming...
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