My buddy had a 42" Vizio LCD @ 60hz (1080p), and recently exchanged it for a 55" Vizio LCD @ 120hz (1080p). The newer one everything just seems smoother. Be it gaming on his PC, his 360, watching a movie (HD or SD), or just watching tv. Over all framerate seems to be higher.
Could just be placebo, but since I didn't buy the tv nor do I care for it much- I doubt it is placebo.