At first sight, I did not like Walzers book. I found his frequent citations of novels, essays etc. unnecessarily pompous and somewhat annoying. However, Walzers book is actually by no means inaccessible to the casual reader, and his analysis is in general clear and properly thought out.
Walzer considers many aspects of the ethics of war. Most of the book is concerned with the question of when and how wars may be just, although considerable time is also given to the question of how a war - just or unjust - may be fought justly. Among Walzers historical examples are the Franco-Prussian war, The six-day war, the Vietnam war, the Korean war and World war II. His themes range widely, including when agression in the face of anticipation is justified, when interventions in already existing wars are justified, whether humanitarian interventions are justified, to name a few. Walzer also considers the rather interesting cases of guerilla war and terrorism, and gives a good deal of attention to the question of justifying civilian casualties.
Walzers book is not meant to be, and cannot in any sense be considered, the final word on the ethics of war. Several of Walzers arguments may be applied to other of his historical cases to obtain different conclusions - one prominent example is the bombing of German cities during the second world war, which seems rather similar to terrorism.
What can be said definitively, however, is that Walzers book is generally well-written and well-argued, provides ample food for thought and clearly illustrates many of the dilemmas of war which are sensed by most people by casual inspection, but which may be difficult to elucidate without considerable thought.