I thoroughly enjoyed this from start to finish. I especially enjoyed the focus on re-framing play as something that can be used later in life and be put together in novel ways to solve new problems (i.e. used to power innovation). It's a refreshing and somewhat liberating thought that one doesn't have to dispense with play as one grows older. I was also nodding vigorously as the authors explored the particularly intrinsically focused rewards of certain types of play; when play is less for others, more 'folded inside' the self. I think this is a rich area that could do with further unpacking; the notion that there is somehow an important (and under-examined) role for 'play' in the construction of an inwardly-oriented sense of resistance (and identity formation) that's experienced during supposedly frivolous activities such as dancing, something that may be as much performed with the body than thought (consciously) with the mind.
If I had one grumble, it would be a predictable one, given my own studies in this area. And that is that the authors had only started to scratch the surface of the vast uncharted waters around dreams, drugs and creativity. Re-framing certain types of recreational drug use as playful activities spawning extraordinary creativity - and in many cases, mind-bending innovation - would, for example, have been a really fascinating addendum to that chapter.
Overall though, highly recommended. The book is written in an open, accessible and thoroughly unpretentious way that makes it a perfect introduction to debates around play and creativity.