This is a solid, albeit shorter than I expected, read for focusing prep time on the most important aspects of a game. The bits on secrets and campaign fronts are probably my biggest takeaways, and make me think I really need to read more of the Dungeon World book. But there's some really good stuff on topics like joint storytelling, combat methods, and player rewards, among other things.
My only real pain point is that it feels very focused on fairly low stakes high fantasy games. Unfortunately, if you want to have a fairly challenging game that is still fun there often needs to be more prep done in places like combat encounters and dungeon mapping. But that's more of a D&D flaw than a flaw of this book, so meh, I'd still recommend this heartily.