My son rode it for the first time (before there was orange and green) when he was 5, and said it was the best ride he'd ever been on. My 4-year-old niece, however, has been on every other ride at WDW (except RnRC cuz she's not tall enough yet) and gets freaked out by the begining video before you even get in the ride at M:S. I've never been on green and the cast members say it's basically just like watching a movie on the video screen.
Jan '07 Pop Century, Mar '07 Day Trip, April '07 Off Property, May '07 OKW, July '07 POR, Oct '07 Pop Century (& MNSSHP!!!), Dec '07 Day Trip
Jan '08 POR
Feb '08 Pop
Mar '08 Off Property
April '08 AS Sports - I think - still gotta book it