Although I really enjoyed reading this book, I was disappointed with the lack of depth in terms of scientific discussion. After reading the description of this book, it was not clear the extent to which the author would explore the various theories of gravity. I taught this topic in my advanced quantum course and looked forward to the author's perspective. Instead the author described the history of our understanding of and philosophical perspecgtives on gravity while avoiding any depth of treatment.
I gave the book four stars because I enjoyed the discussion despite its avoidance of hard science. I will suggest that we understand gravity much more than the author suggests, but because there are various conflicting theories one could in fact argue that we may not really understand gravity at all. But I would argue that science is filled with conflicting theories. Indeed, sociology is still arguing over nature versus nurture, but that does not mean sociology does not have valid theories of behavior.
So I recommend this book despite the above reservations. It is well written and insightful. Just dont expect a comparative discussion of the current theories of gravity.