I'm rather disappointed. The hardback version calls it "The story of the great global catastrophe that spawned...", the paperback title more accurately describes it as "The story of the maverick biologist...". Apparently, the author feels that we are somehow more interested in the life of scientist Paul Hoffman than about the theory that he is putting forth. More science, please, less biography.
A really engaging book, but the most frustrating part is it didn't explain why the snowball period 590 million years ago (assuming it existed, which the book does a good job of convincing you) would have led to such a proliferation of complex life.
Yes, environmental stress leads to new species. But after the thesis given in the first chapter, that this was the catalyst that led single-celled life, which had been quite content for 2.5 billion years, to suddenly go multi-cellular and all specialization cells working together, I think we're owed more.
Wouldn't multi-cellular life with specialization have always worked better? In a late chapter, we're also given evidence that a snowball-earth period happened 2 billion years ago, with the really weak "maybe life wasn't developed enough to get multicellular then." If it's a eukariotic cell, with a nucleus and RNA and stuff, what other magic level is there between that and a multi-celled organism?
Ultimately, it feels like there's a real coincidence of events here that pro-snowballers (that sounds dirty, doesn't it?) figure must have been more than a coincidence.
Still, the geology is interesting, and the process through which this hypothesis (that there even was a period during which the whole earth was freezing) slowly gained traction, makes a good read.