We took the classes the second time around, and my DH who thought he knew everything about NC already, was blown away by how much he learned! He now recommends them to all his friends
Here's the thing - The classes teach you all about relaxation techniques that would be hard to grasp from just reading the books, IMO... also, nutrition and exercise is a huge aspect of Bradley Birth, and your instructor is soo helpful in keeping you accountable and on track.
So, basically, I think the classes are WELL worth the money, and you're OB is wise to recommend them.