This book was hard work to get through. In my view, it had no flow (until the close of part 2), or level of engagement, that you get from the best of the popular science writers, such as Dawkins. I persistently found myself re-reading paragraphs to understand the points they were making, even though I'm familiar with a lot of the terminology and metaphor that often accompanies neo-Darwinian exposition.
Most of the book, put simply, concludes that 'natural selection' can't be the full story in terms of how phenotypes are expressed within a given ecological niche.... So what, Darwin didn't either!
Worse, they didn't 'replace' the idea with anything testable, so it was quite frankly useless as a defining 'tool' to evaluate evolutionary ideas.
As a purely intellectual challenge, it gets my two stars. If it hadn't offered that, well......