It is difficult to rate a book if you basically agree with its main thesis but don't like the way it argues for it. As far as I am concerned, this book is a case in point, as is shown by my rather Solomonic rating. I do think that "surrendering one's will and one's life to a guru" is a very poor decision to make. It may make sense to "turn our will and our lives over to the care of God as we understood Him," as members of Alcoholics Anonymous are supposed to do (3rd step) - an institution that, though doubtless spiritual, not only has no "enlightened master" at its helm but even utterly rejects the concept of a charismatic leader (see tradition 2 [emphasis added]: "For our group purpose there is but one ultimate authority - a loving God as He may express Himself in our group conscience. Our leaders are but trusted servants, they do not govern," and 12: "Anonymity is the spiritual foundation of all our traditions, ever reminding us to place principles before personalities."). It hardly makes any sense, on the other hand, to assume that any of the gurus of the spiritual world is a God in his or her own right, much less to worship them uncritically. It is worth pointing out that this is not a view held by "materialists" only: among many others who take interest in Eastern or East-inspired spirituality, Swami Vivekananda (no less) said that "Of one hundred persons who take up the spiritual life, eighty turn out to be charlatans, fifteen insane, and only five, maybe, get a glimpse of the real truth" (cited by Falk on p. 337.) Besides, there is hardly any way of telling whether or not anyone who claims to have experienced spiritual enlightenment really has or is just pretending or deluding themselves; furthermore, arguably even non-dual enlightenment (or whatever other kinds of enlightenment there may be), all claims to the contrary notwithstanding, does not guarantee that the individual affected by it will behave morally in the future (p. 431-2. I think the case of Zen masters supporting Japanese fascism in the 1930-40ies [researched by B. Victoria] speaks volumes in this respect). Add the human proneness to embarking on power trips whenever possible and forgetting much of one's empathy and care for other living beings in the process (cf. the Zimbardo experiment, related by Falk in ch. 27, p. 305-49), and it will become clear that surrendering one's life to a guru figure, and checking one's critical mind at the entrance of their ashram, is a very risky thing to do, to put it mildly.
The way Falk argues his point, however, is less than satisfactory. While he does admit that he is reporting "allegations" (and often simply rumors) on the gurus he is writing about, he invariably goes on to base his arguments on the assumption that these allegations are true. Someone like me will have no trouble believing that most of them are, but those people who are in danger of surrendering their lives to a guru will hardly be persuaded to refrain from this by such gossipy and one-sided attacks. Falk has obviously gone out of his way to throw as much dirt as he can at each and every guru he could think of; his taint on Vivekananda seems frankly petty and his criticism of Ramana Maharshi is inaccurate (it is the first time, by the way, that I have seen anyone take a shot at this most uncontroversial of all sages). The whole book reads like a rant, and is too long to boot. It is easy, in the middle of the ranting, to miss out on Falk's real arguments (which I have tried to summarize above).
Whoever, after reading this book accurately, reads the negative reviews (I mean those on amazon.com) will see that for the most part they do not address his real points but either ignore them or put forth counter-arguments that Falk has already dealt with. One example: Falk never attacks Ramakrishna just for being a little queer, but because he used other people (mostly children) to live out his phantasies. It is the lack of empathy, of true concern for the feelings and well-being of others, that he sets out to expose, as well as the (ridiculous) contention that some behaviours can only be "misunderstood" in the "perverted West" while (as we obviously are to understand) in the "Holy East" there is no such thing as sexual abuse and the like, which doesn't really deserve a comment. (Or, as Agent Gideon in Criminal minds says: "Evil is not a cultural phenomenon. It is a human phenomenon.") By the way, just because Eastern religious texts praise non-violence and the care for all sentient beings doesn't mean that these ideals are actually realized in Eastern societies, any more than "love thy neighbour" has made Western societies any less cruel. The reason for this is probably that empathy is not something that can be imposed by precept but rather a skill that must be acquired and developed. But as I said, it is easy to overlook the sound points the book makes, since its partisanship is very much in your face and its way of dealing with its sources is unlikely to elicit sympathy and attention to the fine points of the argument from people who do not already share the author's opinions.