It's a nice book, full of very nice information, detailed examples, a lot of insight.
It's well written and fun to read, has nice pictures detailing the author's ideas.
I just found it a small bit too oriented on platform games, and found it a bit hard to bring everything back to a real time strategy, or to be applied generally to every game. While the concept of level is used a lot in modern game industry, it's not universal. Same is true for the hazards, enemies, bosses, camera angles, animations... some of it assumes you're building a specific kind of game.
While certainly worth the money, and a nice read, I would've wanted some more general advice.