In considering the tone of the novel, it is helpful to consider the tone of Yossarian, whose thoughts and statements describe much of the action of the book, and the tone of the narrator, who describes background information but is generally confusing and unreliable. The narrator is usually rather independent and detached. The narrator uses jokes and seems (as Heller evidently does) to enjoy complicated turns of phrase. But in general, the narrator remains separate from the action. Instead, the narrator guides the events of the book by connecting the chapters together.
Yossarian's tone is, often, quite violent and rude. Yossarian doesn't seem to like anyone in the company, nor anyone else he encounters, even the soldiers and others he counts as his friends. He has a special distaste for women; he speaks to them and of them only as sexual objects. The only exception is the case of the old woman at the end of the book, whom Yossarian sees as distinctly pitiable. Orr is the only character who escapes Yossarian's general misanthropy, but Yossarian still uses a tone of superiority in talking to him, since Yossarian thinks he is smarter than him. In fact, Yossarian thinks he is smarter than most everyone with whom he interacts. Sometimes this affects his tone by making him sound conceited and pretentious; sometimes it shapes the tone through his affection for wordplay and intellectual references. Generally, Yossarian revels in his distaste for things, creating a tone of disillusionment and frustrated ennui. This tone from Yossarian emphasizes a feeling of suffering in the war effort and makes the reader feel the war is an inevitable failure led by inept people.