I've read Heller's "Catch 22" first, so Vonnegut's "Slaughterhouse" sounded to me like a deja-vu. The absurdist structure of the novel is amazing but it is stuffed with metaphors and other means of rhetorics to such level that their uniqueness disappers. However, one could interpret abundance of figures of speech in this way: like personages that are not allowed to become characters in times of war, so the words - they lose all their character in the stream loaded with uniqueness.