Warning, gif free review. Sorry. I am SO old school. 
 When I first heard about Illuminae it was described to me as a YA, love story set in a SciFi world. So not one that immediately made my to read list. But having finished A long road to a Small, Angry Planet and really enjoying it AND seeing a lot of run reviews for Illuminae, I decided to take the plunge. Very glad I did. 
 Is it YA? Yeah, I guess. It isn't hard scifi and it isn't Space Opera. It has teen hero's and their love angst is major part of the story, but for me it doesn't feel like Hunger Games or Twilight kind of YA. There certainly is a solid story here, that is told at a pretty fast pace that keeps you interested the whole way through. It reminds me more of Battlestar Gallactica that anything else. Not that it is anything like it, but that kind of feel. 
 The three main characters are strongly written, Ezra the love sick puppy starts off in the first third of the book, quite the character and I was convinced I was going to enjoy reading him. But as the book continued his character became quite static and there was nothing new from him. But still, the writing was strong and believable. Kady was brilliantly written and hugely entertaining. Kick attitude teen girl, who can hack like a demon running amok in the ships computer infrastructure really makes the story for me. Her relationship with SitB was a critical part of the whole story and I think often gets overlooked by the whole "ohhh Ezra, Kady, get it on, you so need each other" story. 
 The third character and by far the best character was the AI (team AIDEN supporter). HAL 9000 has been superseded. If you don't know who HAL is, go look it up and read the books. AIDEN isn't the first to do this kind of creepy shit. Back to AIDEN, A super intelligent AI that has the job to maintain the safety of the fleet. Only that he looks at this task as a whole, not as an individual task. What transpires during the story is that the reader starts to understand the reasoning behind the AI's actions and you really do start to believe him. Which in my opinion is very good writing. You can take a character that you should hate and over a period of chapters start to see the other side. (Glokta anyone?). I really did enjoy the character growth of AIDEN and Kady and it certainly made the book a great story instead of a good story. 
 I am not going to spoil the ending here. Other than to say, I was only luke warm on the ending. It didn't end the way it could have and I was a little disappointed at that. But, this is 
 important 
 . If the next book in this story (after Gemina) is about Leanne and Bitech and the Illuminae group, then I am happy with the ending. 
 Last point. The audio is excellent. A much bigger crew for narration made this like a movie in your head. There is a scene toward the end, where they pipe in classical 
 music and it is very powerful and it certainly gave me a lump in the throat. You'd miss that if you were reading. So if you can get the audio, I definitely recommend it.