"Their Fractured Light" is a satisfying conclusion to the Starbound trilogy. Each book has followed a different couple along a common thread. I do think you need to have read the previous two books (or at least the first one) to understand what is going on in this finale. The first half of the book follows Sofia, a con-artist, and Gideon, a hacker, both bent on taking down LaRoux Industries for the deaths of loved ones. Running from the corporation, Sofia and Gideon must come together and rely on each other.
The second half of the book brings back the four main characters to combat the main storyline from the first two books. While it was great to see the characters from the earlier books again, this meant that the romance between Sofia and Gideon really took a backseat, and I felt like they didn't get as much as their due as the earlier couples. The first book remains my favorite with the great build, strong mysteries, and fantastic romance. The second one felt weaker in comparison, and this third one became more of an action book than having the strong storyline around the sci-fi/mystery/romance. That being said, it was still enjoyable and I think it did wrap up the trilogy really well.
Overall, this was a satisfying conclusion- it brought everything to a head and resolved it. I really enjoyed this YA sci-fi series and I do recommend for people who like YA sci-fi/romance.