I do play games in HD, just not constantly, and have set my settings up to 1080p and really can't tell much of a difference. If anything, everything is much brighter and the text is far more legible, but not particularly "better". In trying to play Tales of Vesperia in HD, I couldn't stand it more than half an hour because it was too damn bright - a bright desert sun turned into a stupidly bright blinding light. Playing Mass Effect 2 in HD just makes it more shiney as far as I can tell - as with Bioshock, Brutal Legend, Saints Row 2, Resident Evil 5, Geometry Wars 2, and most every other game I own. Any visual improvement is really quite lost on me.
Granted, MY television isn't the greatest, but even in watching a friend play his PS3 on a fairly new television, I couldn't find much, if any, difference. inFamous and LittleBigPlanet looked just as normal as I'd seen it otherwise, and equally as good as when played on a much smaller, standard television.
[sub]Maybe I'm crazy :O[/sub]