Katya's World is a true sci-fi, with futuristic worlds at war, undersea battles, lot of technology and even a Leviathan. I really enjoyed this action packed read but at times it fell a bit flat for me, I grew bored even in the midst of battle and I had trouble connecting with the main character. 
 I loved the story as a whole - girl starts her new job with her uncle, expecting her first day to be a simple one. But in the first of many twists, the vehicle is selected by a new officer looking to prove himself and they are ordered to take a prisoner to the prisons. This is the start of an adventure that eventually spirals into full scale war, and the first time we me Kane - who of course is the prisoner. 
 I really liked Kane. He had that complicated character thing going on and he was easily the most interesting character in the whole book. He's funny, sarcastic and brave (when he wants to be) but also selfish and vague. I found myself wanting to stick with him throughout the story. Katya on the other hand, I didn't really connect with until I got right to the very last pages. She's a little stereotypical - young girl trying to prove herself. However, the book did go with the annoying habit of having Katya in the way, all of the time. It didn't seem realistic to me that so many people would just trust the thoughts of a 15-16 year old and let her go wherever she pleased. 
 There were a lot of things in this book that didn't feel realistic to me though and Katya was a small part. The story favoured a lot of twists, characters with ulterior motives, sudden plot twists, big reveals. There was just too much of it and I rolled my eyes on more than one occasion. It got to the point where you could easily guess that if you hadn't seen a character die, they probably weren't dead. 
 I also had issues with the world building. It was vast and grand and well thought out sure, but I found myself wondering about the little details. This entire world is underwater and I wanted to know how on Russalka they managed to make their clothes, food, dyes for the clothes, submarines - where did they find the metal? and even coffee was mentioned. All these little details and no explanation was rather frustrating. 
 Romance? No. The book felt like there was something missing throughout and I think that I'm so used to reading romantic sub-plots in every book I come across, I just expect it now. So I was a little surprised when there wasn't even a whiff and a little sad too, I really love Kane. That said, romance would have got in the way of the story, so it worked well for this book not to have any. 
 Overall, this book did read like the author's first novel, which it wasn't. However it was an enjoyable read and I've already purchased the sequel to find out what happens next, despite my issues with the story! I would have like a little romance but as long as Kane's back in the next book, I'm happy.