I liked Gravano's book. I've heard people say that he lied about a lot of things, but he certainly set the record straight on Gotti. Gotti was a beloved celebrity up to that point that, as far as anyone knew, was one of the great mafia dons of all time. He was a trainwreck, and Gravano spelled it out with information that for the most part was corroborated by court records, wire taps, witnesses, etc.
"...the successful annihilation of organized crime's subculture in America would rock the 'legitimate' world's foundation, which would ultimately force fundamental social changes and redistributions of wealth and power in this country. Meyer Lansky's dream was to bond the two worlds together so that one could not survive without the other." - Dan E. Moldea
