Calling Gravano a hypocrite is just about the biggest understatement of the year. In his book, Gravano denigrates Castellano as a mere "racketeer," while he and Gotti were, by golly, real "gangsters." Then he repeats, verbatim, every word of praise that Castellano ever gave him. He puts Gotti in the same league as himself, a "gangster," then blames Gotti for his having turned rat.
That said, the Kurins/O'Brien book, "Boss of Bosses," paints a pretty dismal picture of Castellano.