2.5 stars
I really enjoyed the first book in this series. While I can readily admit that it isn't a masterpiece, I was kept intrigued and entertained by this story of inter-dimensional travel. Unfortunately, this second installment really missed the mark for me.

What I liked:

1. I did like that we got to see new dimensions. I think the world building is really a strength of these books. We don't get a super in-depth world because our characters are only spending a short amount of time in each place. But the way the author is able to create unique worlds and have them all work within one book is great.

2. In theory, I liked the revelation that just because someone is good in one universe doesn't mean that they aren't evil in another. It could've created very interesting discussions about souls and nature vs. nurture and all that. But did you notice I said, 'in theory'? There's a reason for that.

3. The cliffhanger. I was waiting for the entire book for something like this to happen. If I didn't have the third book waiting for me I'd probably put this in the 'didn't like' column.

4. Conversation about consent. There is a really sensitive subplot in this book that leads to a discussion about the nature of consent. Marguerite is taking over other versions of herself and she realizes in this book that there is a great responsibility in that and also a real chance that something she does could fundamentally change the life of the Marguerite in that universe. Of course, that calls into question the ethics of inter-dimensional travel in the first place. That is only really addressed at the very end of the book, and I would've liked to see it be a more prominent idea in the book, but maybe the third book will delve into that a little more.

What I didn't like:

1. So much melodrama. I don't even know where to start. The first book also had its share of angsty nonsense, but this book was hundreds of pages of Marguerite whining about how Paul wasn't with her in every universe and how could that be because they were supposed to be destined to be together and blah, blah, blah.
Seriously, I am not sure what made her assume that she and Paul have this inter-dimensional connection and that nothing could possibly change that, but it was a ridiculous supposition in the first place. The fact that she honestly believed that in the infinite number of universes that exist that she and Paul are soulmates in every one of them is silly and naive. So when she jumps into a universe where she is intimate with someone else and another where Paul is not a good guy, it completely throws her to the point that she can't be in the same universe as him. It's beyond stupid. Sorry, not sorry.
And the number of times she says, 'My Paul' was ridiculous. I own a physical copy of this book, but I was multitasking (yay, laundry...) and listened to it on audiobook instead. Perhaps if I'd read the physical copy I wouldn't have noticed it. She says it 71 times. Every time she would jump dimensions and meet the 'new Paul' she would spend a good chunk of time comparing him to 'her' Paul. And if they weren't madly in love she would freak out and spend the next several paragraphs lamenting the fact that they weren't together. It got so freaking repetitive.

2. Pacing. Like I said, there is a lot of repetitive passages in this book. It almost seems formulaic:
a. Marguerite jumps to new world, finds Theo.
b. Must give Theo reminder to make him 'her Theo'(my Theo only appears 10 times, but it was still almost as annoying as 'my Paul')
c. Must find Paul and discover how the dynamics of their relationship are similar or different to her and 'her Paul'.
d. Proceeds to whine and complain because everything isn't exactly how she's constructed it in her mind.
e. rinse and repeat.
This definitely throws off the pacing of the novel. It didn't feel like it had to be over 400 pages long.
Also, there is a huge amount of needless exposition at the beginning of this book that is simply the author recapping the first book. I really hate it when authors do this. I know that some people don't mind because they are reading the books as they come out and may not remember parts of the first book. And if we were talking about super specific things I would even be able to understand it. But this book regurgitates the entire premise of the first book. Things people should remember even if they read the book months or even a year before. It's absolutely unnecessary, and it's another thing that made the second book's length seem inflated.

3. Marguerite. I didn't mind Marguerite in the first book. She wasn't my favorite character, but I understood why she made most of the decisions she did and I was able to get on board. This book completely ruined her character for me. She turned into an insipid, whiny idiot who didn't think things through before acting. True, she was impetuous in the first book as well, but she kind of had to be. She was flying by the seat of her pants and learning the ins and outs as she went. The plot of this book required her to use a bit more discretion and discernment, and yet she still jumped in without thinking at almost every turn.

4. Romance. The first book had a romance that I liked and a love triangle I thought actually made sense. I'm not saying it was necessary, but it also wasn't completely pointless or unbelievable. The romance was a subplot to the main action of the book, however. It wasn't the focus. This second book, unfortunately, cannot say the same. It is wholly centered around the romance between Marguerite and Paul. She agrees to do some really questionable things in order to save him. Things that could destroy the lives of people she claims to care about. Things that Paul would never sanction if he knew. But because of her epic love for him (I cannot roll my eyes hard enough) she throws all that by the wayside and agrees to help her greatest enemy sabotage her parents in several universes.
The love triangle still exists too, and we even see a world where Marguerite chose Theo -- something she can't even fathom because TRUE LOOOOOOOOOVE!!! Theo spends most of this book as an afterthought. I'm honestly not sure why he's there except to reinforce a love triangle that has become completely irrelevant.

5. Predictable twist.

When Marguerite finds out that her parents are working with Conley in the universe that is pulling all the conspiracy crap, I wasn't surprised. I expected it would happen, especially since Marguerite has spent the entire book being shocked by the people she knows being different in different universes. It was pretty obvious that it was going to happen, and was foreshadowed with very little nuance.

This is probably my least favorite Claudia Gray book to date. I have enjoyed her Defy the Worlds series and the first of this series kept me intrigued and entertained. I will finish the series and hope that this was just a common case of Second Book Slump.