Just finished. The book is about the way that environment, organisms, and their DNA are coevolutionary forces that affect the development of each other in a complex way that biology (at the time?) was unable to grapple with.

Lewontin's works generally target what he considers to be reductionism in the biological sciences and has informed my perspective on scientific methodologies quite a bit. I think this little book is a good introduction to his perspectives though the Lecture series "Biology as Ideology: The Doctrine of DNA" would also fill that role. If you want anything more indepth the essay collections he did with Richard Levins ("Dialectical Biologist" and "Biology Under the Influence") are very interesting works.

The one thing I'm agnostic about is if the biological sciences still work in the way that he critiques (this book is over 20 years old). In spite of that, I find the ways that he believes genetics and biology should proceed is something I find agreeable.