Eccentric biography of an even more eccentric genius. Following scores of biographies and critical analyses on legendary filmmaker Orson Welles (Citizen Kane, etc.) with yet another life story must have been a daunting task, even for so clever and prolific a film historian as Thomson (Showman: The Life of David O. Selznick, 1992, etc.). Notably, Rosebud has been closely preceded by the massive first volume of Simon Callow's two- volume biography (Orson Welles: The Road to Xanadu, 1996). Thomson, in his far shorter single volume, can't begin to compete with the dense details of Callow's work. Instead he tries a different tack: He blends biography with quirky digressions and diversions. Sometimes he directly addresses the reader (occasionally in the sonorous tones of a Wellesian narrator), and sometimes he conducts imaginary conversations with his ``publisher''—all in an attempt to fathom the compelling, self-destructive personality of his subject. Unfortunately, these asides are often coy, superficial, or redundant. But as he moves deeper into Welles's film work, the digressions begin to drop away, as if Thomson were only distracting himself while dealing with Welles's theater and radio work, in which he's clearly not terribly interested (and on which Callow is brilliant). When he reaches the films Thomson begins to shine. He richly conveys the excitement that the films still generate, and gives provocative insights into their meanings. History and analysis deftly merge in an effective presentation of Welles's erratic final years. Still, the result is more satisfying in patches than as a whole. Perhaps Thomson should have found a forum other than biography in which to express his love of Orson Welles. A mulligan stew of a book that is best read as a complement to, rather than as a substitute for, other books on Welles. (69 photos) (First printing of 50,000)