This one is much better than the first book of the series, in my opinion. The first was just ok and this one was pretty enjoyable to me. 
Definitely courageous of the author to write a whole book starting the series off with a non-endgame couple. I interpreted that as bad chemistry, but it turns out she was trying not to get readers too attached. This whole second book was pretty obvious and predictable but I think it was interesting and kept me engaged because I liked the characters. I also got used to the author's writing style. Definitely skipped through some R rated parts (but even those are less violently graphic in this book than a lot of romance novels these days. So thanks for not assaulting my ears, I suppose). 
I wouldn't call this book a great work of art or meaningful in any way, but as a fantasy romance novel it is decent. I don't know what's coming in the rest of the series, so I hope there's more to come with plot since we've exhausted the intense romance side of things tbh. I'd be happy to see more of Cassian, seems like a character that is getting set up for more face-time but who knows. I'd also appreciate different perspectives like maybe the sisters or someone entirely new.