The sci-fi element of this book is the setting. At it's heart, this book is a thriller in a military sci-fi setting. The central mystery drives the book forwards at a pace. It starts fast and never lets up. The planetside chapters are the most intense action wise, conveying a sharp sense of chaos and immersing the reader into being in the middle of a combat situation. Some people are saying the end comes along too fast, but I liked it - it really forced me to be alert and work out the puzzle myself. This is not a book to read if you want to tune out rather than think or contribute. Mammay doesn't spoon feed the details - I had to assemble the pieces at times. He's not talking down the reader or insulting their intelligence. Of course, somethings are explained, particularly anything technical.