Amazingly, all major characters from the novel went into the movie. The movie is missing some key scenes from the book though. First off is the opening of the book where M packs 007 off to Shrublands. In the movie Bond is there for no apparent reason.
The next cut from the book was seeing the face of Ernst Stavro Blofeld, the leader of SPECTRE. He was very visable in the novel, with a full description. We just see his hands in the movie. Following that, a very enjoyable lunch scene between Bond and Leiter was taken out, because it was tangent and had little to do with plot developement.
The two final cuts were from the climax. First Bond was on board a US naval vessel, recruiting for the fight against Largo`s men, underwater. This scene never happens, in the film and the US soldiers are just there to help 007. And finally the climax in the water featured a terrific fight between 007 and Emilio Largo and ended with Domino killing Largo. In the movie, the setting is changed to the bridge of the Disco Volante.