In his antic all-singing, all-dancing, all-mugging adaptation of Love's Labour's Lost, Kenneth Branagh cuts William Shakespeare down to size to suit a larky artistic vision. He sees the late-16th-century romantic comedy about the amusing self-delusions of young people distrustful of love as a glamorous 1930s Hollywood musical, for which the words by that guy W.S. are okay but not nearly as crowd-pleasing or as sentimentally effective as the music of accessible bards like George Gershwin, Cole Porter, or Irving Berlin. He enjoys Shakespearean declarations okay, but he loves Fred Astairean panache the way he wears his hat, the way he sips his tea.
Characters speak the old man's words (at least a portion of them). But when real effect is called for, they burst into tunes far more famous than the text of this lesser-known play classics including ''I Get a Kick Out of You,'' ''Let's Face the Music and Dance,'' ''Cheek to Cheek,'' and ''There's No Business Like Show Business.'' They dance, too, in elaborately staged, lushly costumed, showily referential numbers closely built on the glorious canons of Astaire and Busby Berkeley; when Alessandro Nivola, as the King of Navarre, and Adrian Lester, Matthew Lillard, and Branagh as his cronies circa 1939, flap their academic gowns as they vow to give up women while they focus on their studies, the boys also recall the venerable work of the Marx Brothers, wreaking havoc at Huxley College in Horse Feathers.
But for every moment of inspired lightness when, for instance, the incomparable, vintage Geraldine McEwan, playing a tutor to the king, sings ''The Way You Look Tonight'' with perfect humor and delicacy to fellow Branagh vet Richard Briers too many moments of evident labor weigh this clever production down. So excited is the filmmaker to exhibit all his bright notions and riffs and homages to Shakespeare and musicals and classic Hollywood (the ending couldn't throw more Casablanca our way than if Shakespeare had written ''Round up the usual suspects'') that each player ends up performing in a different play. Nathan Lane presents the clown Costard as a vaudevillian; Timothy Spall turns the buffoonish Spanish nobleman Don Armado into a Monty Python-skinned loony. Alicia Silverstone tackles the Princess of France as if Silverstone were the cutest girl in a high school production; Natascha McElhone plays one of the princess' entourage with will enough to be a queen, as if the actress doesn't know what she's doing with the rest of the drippy ladies-in-waiting.
Love's Labour's Lost practically pulls a viewer into the pool to join the Esther Williams-style fun, so eager is Branagh to make a splash. To quote the playwright: ''Your wit's too hot, it speeds too fast, 'twill tire.'' C+