A number of positive qualities of the novel make The Chocolate War an easy book to recommend, generally speaking, but there are probably specific types of readers that we can discuss that may be most receptive to Cormier's book.
Some of the remarkable things about this short novel are the ways that it presents a complex character dealing with rather imprecise emotional conflicts. The novel couples this psychological character study with well-defined interpersonal conflict. The combination of these two approaches to conflict give the novel depth and dimensional.
Jerry is a well-drawn character coping with loss and grief. He is also an independently minded young person who stands against the social pressure (i.e., peer pressure) put on by both students and teachers in the school. By fusing the internal conflict Jerry experiences with an external conflict, Cormier successfully creates a very dynamic and compelling story.
This is not just a book about individualism and independence. It is not just a book about coping with loss. It is not just a book about standing one's ground against social pressure to conform. It is about all of these things and, finally, the novel then expresses a thematic idea that personal strength and resiliency can be called on in response to many conflicts or challenges.
These and other aspects of the novel tend to make this a recommendable book in terms of quality. We can also talk about how the novel's focus on young people may make the book appealing to young people.
The Chocolate War takes up high school age youth and school life as its subject. When I was a kid, this book was interesting, in part, because of this focus (and because the novel approaches the experiences of youth with seriousness). There is a sense that Jerry's situation is a high stakes scenario. There are real consequences for Jerry, or at least the novel successfully implies that this is the case.
For young readers accustomed to happy endings and rollicking adventures, The Chocolate War may be a fresh and interesting departure from other young adult fiction. Not to give anything away here, but the good guy does not win in the end in any kind of cut-and-dry or simple way. And the bad guy does not lose.
The novel ends on a note that reinforces the notion that Jerry has risked a great deal to make his stand against Archie and the Vigils.
In fact the book crafts a complex ending wherein the reader is forced to weigh Jerry's intentions against his outcomes. We last see Jerry as he struggles to speak to his friend Goober in order share his hard-won insights. In this moment, he is unable to speak his thoughts and we see them only as an internal monologue on the subject of independence.
"They tell you to do your thing but they don't mean it. They don't want you to do your thing, not unless it happens to be their thing, too. [...] Don't disturb the universe, Goober, no matter what the posters say."