''If there was a Providence coin, Buddy Cianci's face would be on it,'' says one constituent of the politician adored for overseeing the recent renaissance of Rhode Island's pipsqueak capital. Equally admired by gangsters and gays, the corrupt Cianci was elected to a record six terms between 1974 and 1998, half following a guilty plea for assaulting someone he thought had slept with his wife. (He now resides in a federal prison after a racketeering conviction.) Stanton, a Pulitzer-winning reporter, provides an astounding, well-researched account of systematic governmental impropriety. But he fails to flesh out his oxymoronic title character, a sad, needy fellow thinly painted as a huggable, Tony Soprano-like bad boy. More redeeming is Stanton's portrait of Providence, home to volumes of history, throngs of outcasts, and, fittingly, a successful minor-league hockey team.