I found this book to be a page turner. I had previously read Station Eleven so I knew what I was getting into with Mandel's writing; she has an elegant way of writing. The book spans across time and space, but Mandel makes it quite the enjoyable journey. I liked the pandemic based setting because I feel like the book does a lot about exploring the deeper impact of the pandemic on our lives -- for example one of my favorite lines in the book is “This is the strange lesson of living in a pandemic: life can be tranquil in the face of death.” 
Mandel does an excellent job of not letting the science of the story become overwhelming, it was done in a very readable and graceful way. 
I really enjoyed reading this book, but (what seems to be the general consensus) it was really only a four star book for me until the very end. I wrestled with 4.75 or 5 stars, and settled on 4.75 only because I wish the novel had been longer, I would've loved more details/scenes. The way that Mandel brings all the pieces of the story together is absolutely brilliant, and in retrospect, inevitable. I was really drawn into this book and sad when it came to an end. 
Mandel leaves us with some peace of mind about the future, too: "if definitive proof emerges that we're living in a simulation, the correct response to that news will be So what. A life lived in a simulation is still a life"
Exceptional read, and I will be going back to read Glass Hotel now too.