The Quiet American is very much a Graham Greene novel. It is a focused and tight narrative; Greene is completely in control of his materials, his organization, his tone and characters. There is fluidity to the novel that makes it seem easy, quickly won, which is hard thing to accomplish. We see all this in The Quiet American, and also get a wide glimpse of French Indochina just before the American’s took over the war from France. So in this sense, the novel is a great marker of the changes American would endure in Vietnam in the years after its publication.
Greene does advance the end a bit quickly, as if he wanted to finish this novel and needed a device that doesn’t quite work. For the reader, that speedy conclusion takes some of the edge of the work, making it a bit casual. Greene wanted a happy ending but he did nothing to lay the ground work for this outcome. So the end is a letdown.