And sometimes they do the exact opposite. Occasionally, we'll get a demo for a game that we've been following with interest-- the art looks awesome, there are big names attached to it, the music sounds great, the story is interesting; in short, looks like a stellar game, until you actually play the thing and come to the realization that you'd be better off watching all the cutscenes on YouTube than suffering through the game.
Has this ever happened to you? Has a demo ever saved your life (and by "life", we mean "money" or possibly "sanity")? Or have you come across a demo that was good enough on its own that you didn't feel the need to play the full game? And looking to the future, is there anything on Wii that you may want to buy, but only if you can take it on a test drive first?