Just read Iris Murdoch's The Severed Head in two hours flat, a most surprising feat considering I normally get bogged down in her work. But this one just flew by, even though belief had to be somewhat suspended as Murdoch's Greek tragedy style of character interweaving stretched credulity to breaking point. Still, her observations on the state of human consciousness are succinct and accurate, and even though the situations seemed barely believable, the character's reactions to them did. Thus it suceeded as a novel, and even worked sufficiently well for you to care for the protaganists - none of whom are particularly likeable on the surface.
Perhaps her greatest gift is being able to convincingly relate the distortion in thought that accumulates through alcohol consumption. The climax of the book, a violent encounter between the central character and the woman with whom he will be poised to become a lover at the very end of the tale, is very effectively generated. The waves of ever increasing irrationality that drink liberates creep up inexorably towards their high point, and wash away afterwards with equally convincing remorse/self-justification. This alone would mark the book as exceptional.