"Who's That Girl" is no "Something Wild." It isn't even a real throwback to the screwball comedies of the 1930s, although it evokes the 1938 Katharine Hepburn-Cary Grant "Bringing Up Baby" by allotting a major role to a cougar (Hepburn had a leopard) that extricates [Madonna, Griffin] from trouble every time she whistles. Like the screwball comedies, its motor is a wild woman who turns a stuffy man's life into the kind of shambles he secretly longs for. But that priority takes a backseat to the film's more urgent concern -- the packaging of Madonna. In an era where packaging and art are often indistinguishable, Madonna is in her element. She's a performer, and a strong personality -- with her platinum hairdo and jutting chin, she suggests a cross between Bette Midler and an art deco hood ornament -- but she's not an actress. She doesn't know how to play anyone who's not Madonna.