For Darkness Shows the Stars is an interesting book. It wasn't particularly good, but I couldn't put it down! I didn't really like Elliot that much, but I really wanted her to succeed. The romance wasn't my favorite, but I would have been crushed if they didn't get a happy ending. So it was a book full of contradictions for me and I wasn't sure how I was going to rate it until the very end. And in all honesty, I'm letting my emotions do more of the rating on this one than my brain. And sometimes, I think that's ok. So while For Darkness Shows the Stars wasn't technically great for me, I actually really enjoyed it.Here are a few faults I found with the book: 1) There seemed to be a few holes in the world building. I wasn't totally satisfied with the explanation of the Reduction or how the Posts came to be or why the Luddites felt that taking care of the Reduced equaled keeping them as slaves. 2) Kai and Elliot were mostly just bitter, Kai was mean, and they rarely had any honest conversations with each other. I didn't feel much chemistry between them at all. 3) The writing was a bit choppy. Paragraphs and ideas didn't always seem to flow well from one to the next. 4) I was hoping for more of a discussion relating to the slavery issue in the book, especially towards the end when Elliot has more of an opportunity to change what goes on at the estate. But it is never addressed. Nor is the class structure. The Reduced and CORs are slaves, Posts that have run away are workers, and the Luddites are land owners. There is talk of a rebellion, but it never comes. Elliot talks about taking care of the Reduced and Posts on her estate, but she never offers them their freedom. I wanted more from her when it came to this.The reasons I still gave it four stars? The letters. I'm really just a huge sucker for letters. I think it's the honesty that comes out in letters, the raw emotions, the truth, and the lack of wishy-washy feelings that really get me. A character can spend the whole book flipping back and forth on their feelings but they sit down to write a letter and it all comes out. I don't know why or if that's really the reason, but letters (and diaries) just pull me right in. And this book was no different. The look we get at the past relationship between Kai and Elliot through their letters was the best part of the book for me. It's where I felt the most emotions, learned the most about them, and wanted the most for them. The rest of the story was good enough and the supporting characters were interesting (Felicia, Dee, Ro, even Benedict offered something to the story), but without the letters I'm not sure it would have been enough.All of that said, I really enjoyed the book and gave it four stars. I'm excited to read the next one, Across a Star-Swept Sea (based on The Scarlet Pimpernel), though I wish we could get more of Kai and Elliot. The way this book ended was how I liked to see them, what I had wished they had been in more of the book. But I'm sure the next one will be enjoyable with or without them. Because even though I had problems with the book, I still really enjoyed it and look forward to more stories from Peterfreund.Also noteworthy, I have not read Jane Austen's Persuasion, which this book is based on, so I cannot comment on how they compare but I definitely want to pick it up and give it a chance now!