Disclosure: I received a review copy of Ultra Blue. My reviews are always honest and never influenced by the authors.
There is a lot in this book. It's a hard story, and it's a story that a lot of people won't want to hear, but I think hard stories are important. Endings aren't always happy, and sometimes small voices make all the difference.
Sidonie broke my heart. I had to keep reminding myself that she was just eighteen, that she was just a kid trying to figure things out. I remembered how hard I was trying to figure things out when I was eighteen, how hard things were, and I didn't have anywhere near as hard a life as Sid did. There were so many times I wanted to pull her aside and go "No, kid, come on." You just want to protect her. She was doing her best, but she didn't get a fair shake, and our experiences often define the choices we think we have. She didn't know she had better choices than what she got.
If I had to give one critique, it would be that the prose was very literary in style, almost to the point of purple prose or sounding unnatural in first person perspective in some passages, but that's only my preference, not a value judgment. There's nothing wrong with literary writing, and it doesn't affect my rating.
If you enjoy books with heavy themes and don't need your stories to have a happy ending, this is one to read. The last handful of chapters were my favorite part of the book, and the ending was remarkably strong. It took me some time to get through it, partly by my own fault and partly because of the complicated nature of the subject matter, but it was one of my more valuable reads of the past year. I definitely recommend it.