He debunked the "passion hypothesis" and gave practical advices along with the stories of several successful people from real life.
He is vehemently against "follow your passion" advice. He said in his book that if Steve Jobs focused on what he was passionate about, he would be a Zen monk in some monastery, and not a tech billionaire.
I picked up his book because he is a CS PhD and Asst. Professor, and not another 'buy-my-book-because-I-am-successful-in-selling-this-book' guy.
This is a short book and I highly recommend it.
[0]: https://www.goodreads.com/book/show/13525945-so-good-they-ca...