Marko Kloos has a big problem with storylines. In the first Frontlines book, Terms of Enlistment, the plot entirely switches gears halfway through. In Lines of Departure, I'm not entirely sure there was a plot until the last quarter of the book. 
 This isn't to say I didn't enjoy it. I liked getting to know Andrew's mom and seeing him reunite with his girlfriend. But there were a lot of problems, such as (view spoiler)[the unforshadowed mutiny in the end of the book (hide spoiler)], as well as (view spoiler)[the solution to the "we can't kill the Lankies" problem turning out to be "throw a big heavy thing at it really fast!" Humanity really spent five years losing a war without applying simple physics to the problem? Also, multidisciplinary scientists... always a fun trope (although I don't think the physics were any more advanced than the stuff I learned in middle school, to be fair). (hide spoiler)] 
 Andrew is the kind of protagonist I like to call the Jellyfish Hero - he goes with the flow to a fault. Many of the decisions in the book are made for him. His decisions towards the end of the book made sense in that he was following the ideals of someone he respects, but it seemed like a last-minute switch. Is the military incompetent? Is the morality black and white? It changes all the time. I have no clue. 
 I also would like to know more about the Lankies. There's some part of me that thinks it's improbable that a species that enormous could achieve spaceflight, but I was able to maintain my suspension of disbelief. However, they seem very impersonal, and therefore not altogether that interesting. 
 It was a fun read, especially with the top-notch narration in the audiobook, but overall I wasn't too impressed.