I got this for Christmas and read it on the plane during my New Year's vacation. It was pretty good. Not nearly as dense as Bartle's book on virtual worlds, much more concrete than Theory of Fun as far as trying to answer the question of how you actually make a game fun (I do like both of those books but felt like I got a lot more actionable advice out of this one than anything else I've read on game design).
Would recommend to anyone else who's still lurking in this forum and harboring game design aspirations.
"I have not actually recommended many games, and I'll go on the record here saying my track record is probably best in the industry." - schild