I read this book after only having read Rebel's Blade, the first book of the Aermian Feuds. As far as I can tell, you could read this before any of the other books as it mostly is just the same world and doesn't really have anything to do with anything.
That last sentence summarizes the book pretty well. Nothing really happens in the book. After the mess that was Rebel's Blade's "plot," this didn't really surprise me as it was much in the same style. Despite being a novella where the author was limited in how much to really elaborate on different things, a good 80% or so is devoted to awkward sexual innuendo/attraction (including Hayjen's uncomfortably deep affection for a little girl) and reflecting on angst. Despite being much older than the characters in Rebel's Blade, Hayjen still pretty much acts like a troubled teenager, so I think this book still fits the YA bill pretty well.
The best parts of the book are that it actually did SOME world-building, the female lead is decent, and it's short.
Rebel's Blade was so devoid of world-building, it was hard to remember I was reading a fantasy novel at times. Aside from unfamiliar names, there was nothing distinctly fantastical about the world and even mundane aspects of the people and places had no real elaboration. This book at least adds the Sirenidae people as a fantastical race, even if they're basically just sirens whose only defining traits are that they're alluring (they "SMELL. SO. DAMN. GOOD.") and can breathe underwater, have gills sometimes, and apparently get along with whale sharks. Oh, there are also whale sharks. At least I'm guessing that's what the leviathans are. They were only really described as "large" "dark" and as having teeth. Still, this modicum of world-building is more than Rebel's Blade had in a full-length novel.
Lilja isn't really a great character or anything, but she's a vast improvement over Stockholm Syndrome Sage. She's for the most part competent, independent, and unafraid to be who she is. She's still kind of annoying and most of the "plot" in the novel is contrived by her being overly secretive about her people, then eventually shrugging it off so the story can end.
The short length felt better suited to this author's style. Rebel's Blade really dragged on. While it was entertaining in how ridiculous it was, the plot of that book could've been easily reduced to a novella. Even with this book, the plot felt dragged out, despite it being a two-hour read. But at least it wasn't extended even further unnecessarily. If this had been made into a full-length novel, I think it would've been terrible. As is, it successfully achieves "meh" status instead.
Overall, I got about what I expected after Rebel's Blade mixed with a bit of an improvement in character and world. It wasn't a painful read and even the slow parts went by pretty quickly. So I don't really regret reading it, even if it didn't blow me away on any level. My biggest enjoyment, as with Rebel's Blade, was poking fun at how ridiculous and contrived the scenes and characters are. These books make excellent satire. The cover is pretty sick, though I don't think Lilja ever had a magic staff.