I disagree with the last reviewer and find it fascinating that many of the reviews focus on WWI. This book is set against the background of WWI and its portrayals of various horiffic incidents is insightful- but these incidents serve to show us the why and the how of each of the individuals in this book. It focusses on each one, each man as a person ravaged by horror seeking a hiding place from it, but unable to leave behind the stinking, dying flesh of war. Take each man out of the machine of war, and he is no longer a hero among 20 million heroes, but a man. Attitudes towards mental health and duty form the true core of this novel (as subsequent novels in the trilogy focus on sex and then, finally on the mundanity of 'action'). No character is entirely sympathetic, even Rivers, the 'father' at the heart of the novel.
Human flaws are saddening, but also maddening, and the arrogance of breeding (versus the unthinking sacrifice of the working classes) leaves you with some distaste at the actions of Sassoon and others (a man who had not done a day's work in his life until the war came along). Men in Sassoon's position were coddled back to service, while men of lesser breeding were simply shot before they could spread discontent in the ranks.
Barker does not seek to justify anything- you are left to form your own opinions, and slowly cotton on to the fact that neither Sassoon nor Rivers are the heart of this novel, but that Billy Prior, whose life we will follow in the later novels, is the everyman- not a hero, not a coward, not lovable nor particularly handsome, but nevertheless selected by Barker as our guide through the inexplicable horrors of 1914-1919.
I read this recently as part of the '1001 books to read before you die' series, and was deeply impressed by it- having read some of Barker's earlier work I had though that I would hate it. Glad to be proved very wrong!