I believe the structure of The Things They Carried is effective in conveying the entire theme of the book, that being that even though over all war is bad, not every war is the same, and that there are subtle differences between every day and it is that variety which keeps soldiers sane.
	The layout of the book is best described as up-up-down. O'Brien would give you about two nice, not-necessarily-good-but-moral stories (which he claims don't exist), and then he smacks you right in the face with a depressing story or some story that reveals a truth that nobody wants to admit to or talk about.
	Take, for example, the following three chapters: 'Stockings', 'Church', and finally 'The Man I Killed'. Those first two chapters are relatively good; that is, they tell about some aspect of the war that wasn't necessarily bad. However, the third chapter, 'The Man I Killed', is depressing. It chronicles O'Brien's experience of killing an enemy VC soldier and his feelings afterward, which are sorrow and distraught and guilt.