A full summary I think is beyond me: the article's 5 1/2 pages long and densely written. But I can relay a few points. The books reviewed are Beranbaum's Bread Bible, Hamelman's Bread, Daniel Leader's Bread Alone, Mayle and Auzet's Confessions of a French Baker, Ortiz's The Village Baker, Reinhart's Bread Baker's Apprentice and Silverton's Breads from La Brea.
He talks about the difficulties the authors have with balancing the easy-as-pie recipe approach with the reality that making great hearth bread is a very complicated affair. His central point is that much of the information relayed in the books is simply wrong: Ortiz believes fava-bean flour to be a good thing rather than a flour improver "dreaded by every consicientious French baker for its deleterious effects upon taste and texture"; Leader advises adding commercial yeast to a sourdough "in the entirely false belief that it will help to "collect wild yeasts from the air.""; none of the authors understand that using higher protein "bread" flours makes breads difficult to knead by hand and produce "an unpleasantly chewy crumb and a crust that tends to soften and become rubbery" (he advises using King Arthur AP instead).
MacGuire distinguishes between the effects of wild yeasts and lactic bacteria, which I found quite illuminating. He says the "wild yeasts produce milder flavors and a lighter, more delicate loaf, while lactic bacteria produce tanginess and a denser, chewier texture" and talks about how to encourage each. There's stuff on using rye too.
He finds Beranbaum's "dizzying mental calisthenics" ludicrous and worries about the competence of Reinhart, given the evidence of the photographs in his book.
He says that only Leader properly explains the basic temperature formula used by almost every artisan baker but really only recommends Hamelman's book, which he admits is written by a good friend: "The facts and figures are all there, with nothing glossed over, and all is delivered with the voice and personality of a great baker and teacher. His enthusiasm is such that other readers may feel convinced, as I do, that few pursuits are more delightful than an afternoon of baking."