Without doing the appropriate research I have no idea how much of this novel is known or reasonably supposed fact, and how much of it is dramatic licence.
In the author's notes at the end of the book, Marie Benedict says that it is "first and foremost, fiction" but she also says "The purpose of The Other Einstein is not to diminish Albert Einstein's contribution to humanity and science ..." Regardless of that assertion, I would say that a more thorough hatchet job of him, both as a human being and as a scientist, I could not imagine.
As for the prose itself, I found it very stilted - possibly because it was written in the first person. An intriguing read for sure and an interesting choice to write a novel rather than a biography.