Interesting read
I would say 80% accuracy, however to be taken with a grain of salt (age of their friends, neighborhood they are living in, big city life). It's always difficult for me to read books about French culture, as I always notice generalizations, or inaccuracies, or sometimes wrong interpretations.
Fun fact: yes, if you ask me, a French person, "how are you doing?", I'll answer the question honestly. (Can't get used to the American way).