I had taken probability before but not in depth and I want to learn it again. Is David Morin's book good for a intermediate learner ? I don't want to waste time on easy stuff. The reviews are good but popular science books tend to omit proofs instead they just state the theorems and have easy problems. I don't want to buy a book like that rather I would like to have a book that is rigorous and have hard problems. Is David Morin's book fits my criteria ?