First, it is simply a wonderful leadership book that is based on research and observation rather than opinion. I mean, I think behavioral scientists are just as unbiased as journalists, which is to say, not. However, this certainly fits with my observations of groups and leaders over my lifetime and with my observations of myself. It is also a pragmatic book with real strategies to help groups evolve their cultures beyond the ubiquitous "team-building" that seems to only help sometimes, and then only some relationships.
It is very linear, which makes it both easy to understand and apply to what we already observe, so it's practical. That is also its weakness because of course, things move more like spirals and waves but still if a whole group reads this book, then they have a vocabulary to discuss their own dynamics that I think is very valuable. If as many people were reading this as are reading The Art of War, business and education would transform!
What I just said is very abstract and the book is NOT abstract--that is a big part of what I like: an actual concrete ladder from insanity to sanity. I suspect at least one of them as being a Buddhist:)