We're all used to the American-style self-help/management books written by somebody who has little understanding of their subject matter but has sealed a nice book contract on the strength of having talked up their experience to the publisher. Most of them start, "I was once at a dinner party once with <insert famous American here>, and he said to me, he said, 'Bob, let me tell you something which will change your life'..." Most of the authors claim to have run General Motors at some point. Their books are pretentious, yet largely valueless.
If this is your experience of management books then you won't be disappointed with this one. "You Can Negotiate Anything" is stuffed full of vague, unhelpful tips with little or no reference to real-world situations. Although I don't doubt Cohen's experience, he seems to have proven the theory (was it from "Think And Grow Rich"?) that people may know how to do something successfully, but don't necessarily know what it is that they're doing right - the overall impression is that the book could have been written equally well by a jobless student skiving out of a psychology lecture. At best it may help you negotiate £10 off your next fridge freezer. I doubt it would help you negotiate in a business situation.
(To be fair, it may redeem itself in the last chapter, but I gave up around page 215 and went and did something more useful instead.)
If you're still keen to purchase, you can buy my copy.