Anyway -- Non-Zero is a 300-page book with a one-paragraph premise: that human culture (and biological evolution as well) has a stochastic trend towards greater levels of organization, because non-zero-sum parts of the world require collaboration to harvest the (relatively) positive cells in the matrix. While it's an interesting premise, I think it would have gained substantial strength from distillation into a 30-page pamphlet instead, and it doesn't seem to present an argument that would convert those not already very close to the idea of collaboration and cooperation. The evidence presented is anecdotal and handwaving, and seems to thrive on three or four example tribes (the Shoshone of the scrub desert and their rabbit-catching insta-mini-government "rabbit bosses" get a little too much screen time, but nevertheless we learn no additional details about the form of their society).
Wright argues that this model justifies cultural evolutionism, which was rejected in the 20th century as a form of thinly-disguised racism and a justification for imperialism. I am uncomfortable with this argument, since Wright's own model bears little in common with the theories of cultural evolution that the cultural anthropologists of the 20th century so opposed. Wright then assumes that Margaret Mead and Franz Boas would be opposed to his proposal, but many of their objections to 19th and 20th century "cultural evolution theory" do not apply to his proposal. Nevertheless, Wright positions himself as the radical upstart, when it is not at all clear that he is upsetting any applecarts at all.
Wright's writing style has an occasionally off-putting contrast between form and content: while Wright clearly wants to be taken as seriously engaging with the questions of cultural evolution, he also occasionally drops into arguing with sarcastic analogy or jokey colloquialism. While the informality is occasionally welcome, it belies his attempt to be taken seriously -- argument by buddy-ness is not convincing.
Overall: (blackwingedboy take note) don't spend your paycheck on it. If you're interested in cultural evolution questions, skimming this as a survey isn't a bad idea. But it's not a serious introduction to the subject, and its overall argument can (as above) be summed up in a page or two. Despite Bill's interest, this is what libraries are for.