I was debating if I should mention the book, and was worried someone else would.
Of all the negotiation books I've read, it is the best book at explaining the psychological aspects of negotiation. However, the tone and ego of the author is incredibly off putting - especially his continual bashing of the other well known books that are used in MBA curricula. He often makes claims about those books that aren't true and ridicules them (the straws are thick in the book). And then over 80% of what he does advocate is also in those books he criticizes. I usually don't mention the book because I worry that people will read it and have a biased view against all the other good books out there.
As for his "phrasing hacks" - some are great, some less so. I think this is a product of his background - he was an FBI negotiator and most of his negotiations are one-off. He is not going to interact with his counterparts once the negotiation is complete, so he is not aware of the long term consequences. Finding clever ways of asking "How can I do that?" works in the short run, but will often damage relations in the long run - people do wisen up to it. These days I have to deal with someone who keeps asking what the author would call "calibrated questions", like "Yes, but how will I know X?". I'm at the point where I just respond with "Yes that's a good question. How will you know X?". And likewise to all the other questions.
Some of the calibrated questions are really effective. Others are not. I suspect because most of his interactions are one-off, he cannot distinguish.
One of the books I read (Bargaining For Advantage) formalizes this a little: You have two axes and 4 quadrants. One axis is: How much you care about the outcome. The other is: How important is the relationship to you?
The toughest is when both are important. The quadrant where you care about the outcome but not the relationship is easier, but can be challenging too (examples are divorce and negotiating the price in a market). When the relationship is important but the outcome isn't, the advice is to focus on making the other person happy - this can also be the perspective of an employer who wants to hire a good candidate - if the candidate asked for an average salary or less, give him an above average salary. For the final quadrant where neither is important, society usually has protocols that people just follow so that time isn't wasted on negotiating trivialities.
But I agree - there is good stuff in the book. And of all the ones I've read, it is the most "down-to-earth" in terms of putting what you learn into practice.