Just got the Dec 2011 issue of Latin American Antiquity. This allowed me to complete the book review graph through 2011. This graph shows the number of book reviews published per year in the journal:
This really steams me up, and I've complained about it before; see some of the posts listed under "book reviews" in the list of terms on the right side of the blog (scroll down).
We can't trust publishers, even academic presses, to not publish bad books. Yes, most book manuscripts are reviewed by outside reviewers, but a good number of real stinkers (and lots of pedestrian yawners) get through that process and are published each year. So how does the discipline exercise quality control with respect to books? This is a prime role for book reviews in peer reviewed journals. But if the major journals refuse to publish book reviews, the discipline suffers. My field, Mesoamerican archaeology, is particularly badly served by its major journals. Ancient Mesoamerica refuses to publish any book reviews at all. And Latin American Antiquity does allow book reviews, but now they only publish a few reviews each year (see graph).
If you want to see a really bad book criticized in a zinger of a review, check out Richard Blanton's review of a new book by Charles Maisels in the online journal, Cliodynamics.