The book can be boiled down to a paragraph: there are three kinds of motivational priorities, each requiring that the prior be met (think Maslow’s needs). Motivation 1.0 is primary drives of food, water, sex, shelter, etc. Motivation 2.0 is secondary drives: extrinsic rewards and punishment, usually monetary. This form of motivation usually follows the carrot-and-stick model and is useful for tasks requiring routine, noncreative work. Motivation 3.0 is intrinsic motivation, relying on autonomy, mastery, and purpose. If Motivation 3.0 is employed on a heuristic task (the creative, unique, problem-solving variety) than it will facilitate happy, productive, and motivated work.
Really, that’s about it. Pink goes on to share some real-world applications and demonstrations of this, but it’s largely for the business type. The “surprising” conclusion is that people are more motivated in certain (heuristic) kinds of tasks if they are rewarded not with more money or more vacation, but with a greater degree of autonomy and purpose in performing the task. There’s even a summary chapter at the end of the book, for those who want a tl;dr written by the author.