`Beetlejuice” gets off to a start that’s so charming it never lives it down. The movie is all anticlimax once we realize it’s going to be about gimmicks, not characters. During the enchanted opening minutes of the film, we meet a young married couple who have just moved into a strange new house, and we’re introduced to some of the local townspeople. All of these characters have an offhand, unforced innocence, and no wonder: The movie was directed by Tim Burton, who created a similar feeling in “Pee-wee’s Big Adventure.” It’s hard to describe what makes the opening scenes so special. Alec Baldwin and Geena Davis, as the young couple, seem so giddy, so heedlessly in love, that they project an infectious good cheer. The local folks are so gosh-darn down-home they must have been sired by L. L. Bean out of the “Prairie Home Companion.” The movie is bathed in a foolish charm. And, fool that I am, I expected that note to be carried all the way through the film. But it was not to be.