I seem to remember another thread about this book, although I'm fuzzy about the details. If it is the book I'm thinking about, it isn't bad as far as books of its calibre go, I remember looking at exerpts of it online. It is short and to the point and seems to be made with readings in mind rather than the bigger picture of structure and symbolism. I remember serious problems pertaining to its editing (direct translations, funky syntax and typos) but that's forgivable.
The main problem, though, with books about the "big" decks like the RWS or Thoth is that these books very often reflect the authors' own views about the deck which are very often at odds with the original intent of the decks' creators. On the one hand one may say that this doesn't matter because of intuition, etc. I support that view somewhat, as even the creators of these decks were aware their ideas would be developed through iteration and use. The authors of this book seem well-read and I have no doubt that there is something of the Ring Cycle in the RWS, or at least the ideas, symbols and worldview that govern the backgrounds of both.
However, lacking any formal kind of citation of sources, one can only conclude that despite the bombastic name, the book isn't very "Waite-ish," which is a shame since the deck is. Very much so, in fact. Many symbols are far from universal or traditional and are used in different ways that may not be readily apparent. And if the views presented in the book are the authors' own then the book seems superfluous to me because anyone can do what they did, to journal the different symbols. There's no "magic" there, nothing to elevate this book from others.
Ultimately the question that should be asked is if one is really interested in these authors' vision of the deck, or whether they want to know what's actually going on there. Nobody is under the imperative to become a Waite scholar, but one should not delude themselves that this book is anything close to the "ultimate" book, or even in the neighborhood of authenticity. Rather, it an interpretation of the deck itself, using whatever tools the authors had at their disposal. As good as an interpretation may be, it is still second-hand.
Our own Abrac has done some marvellous research over in the RWS forum about the sources and influences of the images on the cards and has suggested some ideas that, supported by the source material, seem very likely to be true. Waite was a highly prolific author, and much about the deck can be gleaned from others of his books. If someone really wants to do the work and find out, the material is there in Waite's body of work. It isn't easy, but anyone can do it.