This is not an easy book but it is important to the bidding process and I know of no-one who investigates how the value of a hand changes as we hear other people bid as well as Mike Lawrence does.
This author writes very good books, but I was disappointed in this one. It might have been the topic does not lend itself to more quantification, but I expected to see more specific quantifiable evaluations. Instead, an example would be given and then the evaluation would be, this hand is now worth less or worth more, but very seldom did it say by about how much. The copy I read was published in 1996 and it didn't seem to have updated some of the bidding examples from the 1970's. The book did make several good points such as the value of the hand can change with each bid and that the process is one of constant reevaluation.
This was a good learning experience, although I didn't find it quite as useful as Judgement by the same author. It was a lot of hands to read through one after the other.