I struggled with the historical textbook descriptions at the start of each chapter, and felt the execution took away from the story. I've enjoyed other books with a similar approach, like How To Murder Your Employer, so I'm not sure where this one missed the mark for me. 

I also struggled with the term multiverse because it didn't align with all the other uses of the word I've seen in popular media and so the book felt less complex/fantastical than I had expected it to be. That's probably my own bias though.