Solid, but (1) this really could have used a good editor, and (2) it doesn't quite live up to the hype, and (3) if you read a lot of social science, a lot of this won't be new to you.
I normally love books that can be described as "like reading Downton Abbey," but I think the genre of "we're going to focus on a woman peripheral to a famous person and show how she changed history" has been overdone.
I really, really enjoyed this. I will definitely be looking for his other books. It felt like much more than just a genre mystery. There were all sorts of interesting issues here and well-developed characters.