It sounds like you are concerned that your manager will figuratively if not literally throw the book at you if you disagree with him. That's rather ironic in light of the fact that he is supposed to be a better manager as a result of having read this classic in the first place.
You do not have to say that you liked a book just because your manager loved it. However, in light of his state of enrapture, you may want to be rather discrete in describing your feelings about it.
Looking ahead to the meeting, since your manager is so smitten with the book, you can expect him to do most of the talking. This means that you should be in a listening mode, armed with several questions that show that you read the book and are interested in your manager's thoughts.
If he asks you a point-blank question regarding your opinion of the book, you should open with a positive comment about some part of it, difficult as that may be. As for the parts that you did not like, be sure to avoid using labels such as "simplistic" or "contrived," and try to phrase your comments as questions, such as, "The section on X seemed to overlook Y, didn't it?"
By listening to your manager, your opinion of the book may become a little more positive, and your manager's opinion of you may become a little more positive, too.
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