I don't think that's fair. The majority of the book is a straightforward history of money that doesn't accept received wisdom. Near the end, the author's more anarchist leanings color the narrative. The last two chapters are not as informative, but that doesn't mean one should discount the majority of the book.

A few takeaways I have from that book: 1) In rural/traditional societies, debt (measured and stored in people's heads) and other reciprocal social obligations were enough to run an economy. Simple example: you give your neighbor some grain when the harvest comes, and you neighbor repairs your tools the whole year long. The classic economy-textbook idea that we invented currency so we don't have to barter with the goods we produce has never been observed in history. 2) Governments induce the creation of currency. Any government can change the currency by requiring the repayment of taxes in that new currency. Often this is for the purposes of paying armies. 3) Traveling merchants need to use currency because they can't rely on social obligations at each place along where they travel. Money allows anonymity.