There's some great advice here for recognizing that the story may diverge based on what players may do, and that the players should be the stars of their own story. But where this book falls down is the "free association" part of the title. A short list of keywords is presented at the end, and there's talk of using them randomly, and that's about it. The advice on "don't over-prepare" is particularly good. Free association needs to be building on what the players are already doing, and there's not a lot of advice on how to deal with players going off on tangents. For all the talk about procedural generation, there's very little here. (And even less, if you're not interested in fantasy.) "Elegant Encounter Design", by the same author, has better advice for how to structure stories around branching paths.
[2 of 5 Stars!]