As a huge fan of both the book and the film, I loved reading about how the movie was made from the perspective of someone who was really there.
Although most of the anecdotes were already well-known, what I liked the most was realizing that each actor in that movie is just as in love with it as we are as spectators. The script (and the book) is William Goldman's favorite thing among everything he's ever written. Rob Reiner still claims it was one of his favorite movies. For the whole cast it was an incredible experience. It really is just as special for them as it is for us, and that is amazing. Cary is such a sweet guy, I'm very happy I read this.