*Read for the 2016 reading challenge: A science-fiction novel* 
 This book was really excellent. I was afraid of the format at first, usually I don't like books that are composed of letters and 'files' etc. But I also read some reviews from people who are not into that either but still enjoyed this book. So I decided to give it a go. I do have to mention that this is the first sort of 'space adventure' that I've read, which definitely influences my review. 
 It started of a bit slow for me, but I kept on getting more and more involved with the story and the characters. I loved the simple humour, used in the chat conversations. The action, wow. The 'love story', which was not too 'sweet' (which I think can happen easily in YA romance) since the main characters are not even physically together and there was not too much romance to distract from the story. In the second half there was also quite some creepiness in there which really got me on the edge of my seat. 
 Overall it is just an epic space battle with so many characters and layers and plot twists. I think the format really helped convey the story. Because there are so many characters and so much stuff is going on, it helps that it is told from different perspectives that have a large overview of the events. For example, there are descriptions from camera logs which show what is going on on a specific spaceship, rather than one person telling what he or she sees. This is probably an odd comparison to make, but for me this format worked better than the format used in "Miss Peregrine's Home for Peculiar Children" (which uses 'old' photographs). When reading that book, I got the feeling that the author just made up of pieces of story that were unnecessary just to be able to fit in a specific photograph. With Illuminae, I had the opposite feeling, that the format was used to be able to tell the story. There was never a point where I felt that the authors made up an extra event or character just to be able to use a cool looking map or view of space, etc. 
 One of my favourites!