The book talks about all the stuff about web design that you already know but don’t think about often enough. The idea is to make the user journey so intuitive and simple that the cognitive load on the user is at a minimum. This is achieved by reusing common patterns and sticking to tried and tested formulas for features which users have become accustomed to seeing on websites — navigation, search, login forms, etc. By sticking to the formula a user is less likely to find have any difficulty in getting from point A to point B in their journey.
While the book doesn’t offer any groundbreaking new information it serves its purpose well as a reminder of all the best practices to follow when designing and building successful user experiences.