Some nice, and for the most part reasonably accurate factoids, but ultimately let down by poor/simplistic science, contrived and pretensious mathematics and some well-masked circular reasoning.
On the plus side, few actual conclusions are drawn; rather the oh-so-important implications and suggestions are left to 'speak for themselves'. Something they utterly fail to do of course, unless you've already bought into the nonsense and have suspended critical faculties.
Reference to mystical ratios etc. are amusing (or amusingly naïve?): Nothing more than numerical coincidences and contrivances, and as any half-competent amateur astronomer knows, what may be more or less true at this point in history wasn't earlier, and won't be again in few centuries or millenia. So there is no awe-inspiring existential significance whatsoever. Nothing especially special about the geometry.
That said, there's not a great deal which is actively or spectacularly 'wrong' in this book, but there's even less which is valuable, insightful and 'right'. A good book to read if you want to do the debunking sums yourself, but in the end about as intellectually satisfying as finishing a half-completed 'medium' sudoku.
Were it not for the studious hat-tipping to various fascinating ancient calendars, I'd definitely say don't waste your time. As it is, I'd say that these are the most interesting parts by far, and can pique your interest, but equally there are far better treatments elsewhere, and which forego all the twee piffle.