To be honest, i was doubtful at actually spending out any cash on a book, since i thought you could probably get all the information you need on this subject on the net. But the internet stuff i found was either very partial or was impenetrably technical.
I would advise you to save your time and make the initial (and tiny) investment on something that will set you on the right path.
If you want this book to learn how to memorize the cards, then it does just what it says on the tin. It does so in a manageable and easily understandable way.
I, however, was more interested in understanding the techniques and seeing where else they could be applied. Which brings me on to my main point:
I think where the author stands out remarkably is in the after-sales. This is the start of a journey that the author is willing to accompany you on. This is not a fully comprehensive manual on memory (nor do I imagine it was intended to be), but whereas other books might leave you wondering where you might go next, Anthony Metivier will leave you wondering which of the many routes he indicates you want to investigate. But he doesn't leave you wondering long, as he eases you in the right direction and may even be waiting there to give you yet more information when you get there. Along with the text, he provides you with numerous newsletters and links to videos and other free sources. I can't imagine that he is always able to enter into personal correspondence with everyone (maybe he does) but I contacted him with questions and was delighted that he was able to answer. Usefully and at some length. I understand that his methods both draw on the conventional knowledge base, but are also unique (and, importantly, encourage you to be unique) in the way of tackling memory to make the results lasting.
It seems evident that the author is both authoritative and completely absorbed by the subject. I really think you have nothing to lose and much to gain by buying his book.