Seems like some really solid advice overall for a player-goal-driven campaign. The advice is actually less about what might come to mind when you think of roleplay—eg. character emotions, encouraging players to take and give conversational space, accents, etc.—and more about all the ways a DM can make it exciting and easy for players to really take to the story and drive that with their own interests. I haven't had the chance to apply the learnings yet, but I've already felt inspired in my own planning process for an upcoming campaign. It feels like a lot of ideas in this book would yield fun, exciting results.
Some of the advice does feel a little shoehorned to fit into the book's theme of making the campaign player-driven, and is more so just good advice in general. But that's hardly an awful problem to have.
They even include a one-shot example of how to create a player-driven story... which is impressive given that these authors don't have the benefit of, you know, like actually talking to your players and asking them what their goals are. The result shows how you can have some great, malleable ideas for a story, and adjust them based on what players might be most interested in.
Overall, really great little guide - highly recommend picking up, but might update this review after making use of some of the material.
PS: For best results, consider picking this up before doing *too much* campaign planning, since some amount of the content, while effective regardless, is probably *most* effective if you take it into consideration from the very beginning.