I received an advanced copy of this book from the publisher via NetGalley.
It's a little unfair to have read two novels nearly back to back with such a similar premise (jumping through different books) and to try not to compare them, but this one blew it out of the water!!!

I was a bit leery at the beginning of the book, realizing that it starts with a suicide. I wasn't sure where it was going to go from there. It was a present topic in the books, but it wasn't graphic. So just a warning to those who might be triggered by that.

It feels odd to say that a book that centers around a suicide has an inspiring message and optimistic ending, but it does.

The Midnight Library is a place where Nora can explore her life regrets and live a life that would have resulted from making different choices in those instances. It is a story of parallel universes/sliding door actions. Nora has the opportunity to see what her life would be if she chose differently. But she is put into the life at the age she is now, not the age of what where she was when the "regret" happened. And she does not enter those lives with previous knowledge of the events that transpired in that life. I would personally find that difficult and that I wasn't worthy of that life, that I was an impostor.
The further she goes on jumping through her other lives, Nora makes discoveries about herself and her pull to actually want to live. And how she wants to live that life.
Another theme heavily discussed in this book is mental health. There is discussion around depression, panic attacks, anxiety and medication. Other reviewers have talked about Matt Haig's personal experiences and past history of these topic being in his books. I was unaware of either of these facts, but it does make me want to explore more of his work.