Well first of all, it needs to be mentioned that Volume I and II comprise one big book, and they're not sold separately, so this review naturally applies to both. I got this to get a closer idea of McCarthy's radical stabilization theory that challenges neo-Darwinism from a completely different angle than I've ever previously encountered. This is no mere tinfoil creatonist hogwash, but a thoroughly researched analysis of a phenomenon that hasn't been seriously considered a potential player in phylogenetics before as far as I can tell (outside of bawdy comedy). While some of his conclusions don't sit quite right with me for reasons, the general picture he paints seems logically sound, and I do believe that anybody who challenges the Goliath of dogmatic science with professionalism on his side is deserving of at least a nod of approval, even when I remain skeptical about them in this one case.
The major bulk of the two volumes is comprised by an exhaustive list of alleged cases of hybrids across the whole span of human literature, perhaps the most exhaustive catalogue of its kind ever assembled, and even if you don't subscribe to McCarthy's theories, the book can still serve as a valuable resource for this phenomenon if nothing else. Beware that most of the book makes for some quite dry reading, as the endless citations of eyewitness reports of monstrosities from centuries past eventually start to blend together without adding more to the suspension of disbelief, and the notable takeaways are almost completely squeezed into the 100 page conclusion, the topics of which I believe might be better articulated in McCarthy's other book, On the Origins of New Forms of Life, which I'm yet to read through. It reads less like your everyday popsci book and more like a 900 page science journal article.
I guess that McCarthy's own prose might be his biggest flaw, as while he eventually does address many concerns and nitpicks I have with the fundamentals of his theory, he definitely takes his sweet time to get there, and in multiple cases he left me hanging for 50+ pages thinking "this guy is just totally gullible" before finally getting to explain himself. I believe a more biased or less interested reader would've dismissed it way before that point. Also the book's graphic design... definitely needs work. I mean, the front and back covers alone are pixelated and have JPEG artifacts, and that's just the cover. Nevertheless, if you want to find out about something baffling, eye-opening, teetering right on the edge of crazy and yet oddly sensible, you might try getting yourself familiar with McCarthy, but only with an open mind. Consider starting with his website: http://www.macroevolution.net/