This book wasn't for me.
   I'm a character driven reader and all the characters in this book were so one dimensional it hurted. Like, I get that the main focus of the story is the war, but some of the characters we spend more then half of the book with and they are as flat in the end as they were when first introduced and because of that I ended up not caring when someone died.
    The main character clearly had what I like to call "action anime male protagonist symbrome", with includes: plot armor so he doesn't die even when he should, being perfect in everything he tries to do and having hot woman interested in him just because. I didn't hate him, but I also didn't like him, he was just a bland protagonist. 
   Also, the author seems to be very confused on what type of book this is. He seens to be writing a fantasious story with unrealist alien science, with is totally fine, but then he tries to explain away the craziness like it is real Earth science and it gets really confusing. Especially because the tone of the story is all over the place, going from stupid jokes to action packed scene to stupid joke in the blink of an eye with paragrafs of science throw in the middle. 
    It poses some big questions, like: Is colonizing space by killing entire aliens species ethical? How much can you alter your body and self until you are no longer a human? Etc. However, those questions are never answered. The war is just there and that is not good considering that said war is the center of the plot.
   The only saving grace for me was Jane and her relationship with John. Wich didn't help much since she only shows up in the last, like, 10% of the story. Honestly, if the book was told from her perspective I would have enjoyed it more. The whole concept of the the Ghost Brigades was interesting, but,  unfortunately, not interesting enough to make keep reading the series.

A really great entry into a broad science fiction space exploration series. Not heavy on the science detail but uses that as a backdrop to explore the ideas of what it means to age as well as what it means to go through different stages of life. This is all done through a pallet of cloning and military service. A good and easy read.

I'm not usually a military SF reader but I got curious about the premise of the "second life" that elderly retirees can get by enlisting. It's a good hook.

I'm surprised how many reader reviews tagged this as funny. Just because of some dialogue wise cracks? When

quite a few likeable characters die in various unpleasant ways.

I found the thread about John's love for his dead wife rather moving... right up until it became clear that she was going to be replaced on a particularly appalling way. I wouldn't have minded a new romance when John's been a widower for nine years. But this:

a clone of the dead wife, who is emotionally six years old, whom John is teaching/grooming with memories of his wife. What.

. I'm not up for it. The romance doesn't progress in this book, but we get enough to know that's where we are headed.

It's too bad I have to bail; I see that the sequel has alien POV which is intriguing.

A very dark military sci-fi book that’s strangely uninterested in questions of morality. The main character literally commits war crimes against various aliens, and even discusses the fact that humankind has basically gone to war with every other civilization in the galaxy just because we can, but it’s kind of… shrugged away? There’s a character who’s planning to become a military leader and then end the wars, but she later dies and it’s really not discussed any further. It’s a good book, but I wish it was a bit more thoughtful. 

While Old Man's War brought very little to the table in terms of new ideas to the sci-fi genre, it executed tropes well enough to remain enjoyable. The plot was a touch predictable, thanks to the numerous info dumps meant to hold your hand throughout the narrative, but the wit in the prose continued to hook me again and again.

If you are giving this book a shot and find yourself struggling in the beginning, the story drags its feet (imo) until about 60% into the story. Then it actually gets interesting beyond the whole training montage sequence the story is up until then. At the same time, the fact it took THAT long for me to finally not put the book down isn't great, either.

There's more to this series, but I'm not really jumping to find out what's next. Maybe I will someday. For now, I'm content with what I read and shall move along.