Coleman's history is a wonderful example of balance - It's a book about comedy, but also about the broader American cultural context, it's about individuals and ensembles, it's about grand ideas and the practical realities (and egos) that constrain those ideas. I really appreciated Coleman's willingness to venture her own opinions about improvisation - by having a clear idea of its ideals, she can better track its betrayals - without losing sight that this is fundamentally a book about a handful of nerds from the Playwrights Theatre Club at the University of Chicago.
I read Sam Wasson's Improv Nation before this and it struck me that most of the major tensions in improvisational history were all evident in its earliest years. One notable exception: The glaring exception that Improv's cultural criticism was entirely organised around Marxist lines and seemed aloof to the struggles of both women and African Americans - though this is a critique of improv itself, not Coleman's retelling.
Wasson's history (Improv Nation) is longer and better traces the impressive, star-studded history of improvisation: From stage to screen, from small theatres to big industries. Yet Coleman's history is more intimate, more ideological, and in many ways gives the reader a much more alive sense of what improvisation is and where it may be headed.