It´s an interesting book, since the method is good for presenting.
However, instead of buying the book, perhaps I would rather participate in a session/workshop applying it -it´s the way you truly learn it, at least it was like this for me-.
If your question is whether this is useful to apply to consulting, I would say close to zero. It´s a great communication training, but you need much more than that: that one is only a little piece of the whole thing.
Hope it helps!