First off I loved the book, I don't think it's perfect but I think Paloni achieved what he was going for here and that's why I give it 5 stars.
The world is building here is the best part in fact I would say the book is more about the world and the way it develops rather than about Kira herself. To me, everything about the world is memorable, every ship, building, and piece of technology I can understand and remember with vivid detail. I think that's a more impressive task to accomplish as a writer; making the world and inanimate objects as interesting and dynamic as someone may write characters.
In general, the plot is hardly driven by Kira's motivations it's almost as if Kira acts just how humanity would, kicking screaming, and trying her best to win because it's necessary. I don't think this is bad though, some people seem to have a really bad taste in their mouth because they didn't enjoy the characters or didn't feel like their motivations stood out, but I don't think the story was supposed to be character-driven. In the end, Kira's personal motivations and ideals do tie in nicely to how and why she succeeds but throughout most of the book, the focus was humanity and the world at large. This isn't necessarily bad though nor is it atypical for sci-fi.
That being said I still think the characters are super lovable and enjoyable. I fell in love with the crew of the Wallfish especially Falconi and Gregorovich. I think the crew has such a beautiful dynamic with each other and I would also love to see more of it but the story just wasn't meant to focus on them alone.
I personally think a lot of the negative reviewers came in expecting the same level of character detail as in The Inheritance Cycle when it just wasn't what Paloni was trying to achieve, but that's just my opinion.