For each of his ten chapters, Wexler examines the "odd clause" in question and draws out the larger constitutional principle at stake (using the titles of nobility clauses to discuss federalism, for example, and the incompatability clause to talk about separation of powers). He also usually discusses any relevant jurisprudence or debates that have sprung around the clause in question, and often spins out some hypothetical scenario in which the clause could one day be front page news (say if Ron Paul were to get his way and the government began issuing letters of marque and reprisal to private companies so that they could hunt pirates off Somalia).
While the zoo analogy does wear a bit over the course of the book, and Wexler's style of humorous asides may not be to every taste, I certainly learned something from this book, and would recommend it to anyone interested in a quirky overview of American constitutionalism.