As a description of a language it's extraordinary and alien, but as ethnography or game theory I find myself disbelieving it. A culture that has no sense of measuring value in an exchange? Is this Everett some sort of Margaret Mead dupe? The whole thing reads like a deliberate Borgesian fantasy about some impossible Uqbarian society that violates the rules of human thought. Well yes it would. Because that's what he's claiming they are. Fascinating -- dubious -- needs further study.
Bai baina. Mark Liberman in Language Log assures me Everett is pretty sound as a linguist. And I find his description of Wari' in The Handbook of Morphology eminently sensible and sober, so it looks like I have to get used to my eyes bugging out over Pirahã, which is about to get very famous indeed, even in the Muggle world.
Ez bakarrik. Language Hat points out it also contains a completely new sound, despite having the simplest phoneme inventory known. And Everett thinks they didn't use it in front of him for many years before because they knew it was strange and didn't want to be laughed at. This is scary too: because the culture is so fascinating we need lots of people studying it, but would it destroy it if we finally did convince them to learn Portuguese and arithmetic? Thankfully they seem robust against intrusion.