[In You're a Big Boy Now] Coppola shows a fine feeling for New York's grimy excitement, especially in a sequence in which his young hero peeps in and out of porny book stores and amusement parlors on 42nd Street; the cinéma-vérité casualness, bouncy editing, and Lovin' Spoonful music nicely render the city's exuberance without skimming its sordidness. The story, what little there is, concerns a boy's effort to break the complicated parental bonds (his ambivalent feelings toward his father are suggested by his chronic inability to decide what to call him) and discover sex. It is not the freshest idea in the world, but Coppola has enlivened it with amusing details…. Coppola's invention and energy run down about halfway through the movie, and he tries to recover with an arch, frantic slapstick chase. (The rediscovery of Mack Sennett has been one of the most disastrous influences...