i found this:
Based on a memoir by former undercover cop Joe Pistone (whose daring and unprecedented infiltration of the New York Mob scene earned him a place in the federal witness protection program), Donnie Brasco is like a de-romanticized, de-mythologized version of The Godfather. It offers an uncommonly detailed, privileged glimpse inside the world of organized crime from the perspective of the little guys at the bottom of Mafia hierarchy rather than from the kingpins at the top. Donnie Brasco is not only one of the great modern-day gangster movies to put in the company of The Godfather films and GoodFellas, but it is also one of the great undercover police movies--arguably surpassing Serpico and Prince of the City in richness of character, detail, and moral complexity. Donnie (Johnny Depp, a splendid actor) is practically adopted by Lefty Ruggiero (Al Pacino), a gregarious, low-level "made" man who grows to love his young protégé like a son. (Pacino really sinks into this guy's skin and polyester slacks, and creates his freshest, most fully realized character since his 1970s heyday.) As Donnie acclimates himself to Lefty's world, he distances himself from his wife (a terrific Anne Heche) and family for their own protection. Almost imperceptibly his sense of identity slips away from him. Questioning his own confused loyalties, unable to trust anybody else because he himself is an imposter, Donnie loses his way in a murky and treacherous no-man's land. The film is directed by Mike Newell, who also headed up Four Weddings and a Funeral and the gritty, true crime melodrama Dance with a Stranger. --Jim Emerson