Wow... that was so beautiful and so bleak all at the same time. The 5th Wave series has always been rather dark considering it involves child soldiers fighting off an alien invasion that has already obliterated 99% of the planet's population. So to say this book is bleak is really saying something. The thing that really makes this book so amazing is how lyrically poetic the tragedy is portrayed. It makes you find the beauty of all this chaos and pain. Which is the exact thing the book is trying to get across. There can be no joy without pain. There can be no hate without love. Humanity is what makes us human and a human without humanity is something Other. The sum of one thing is the sum of all things. 
 So there you go. You can love the good in us and hate the bad, but the bad is in us, too. Without it, we wouldn't be us. 
 Sam: He had a couple of chapters from his perspective (IE Chapter 38. Which is the best damn chapter of this whole book!!!) and it was so unique. He's 6 and a trained soldier. He can't remember his alphabet but he knows how to make bombs. The way his mind processes things is just so utterly fascinating. 
 In the instant before he pulled the trigger, he remembered his mother's face, the face they had given her, and the bullet that tore down the barrel held his rage, bore his grief, contained the sum of all he had lost. It connected them as if by a silver cord. When her face blew apart, they became one, victim and perpetrator, predator and prey. ABCDEFGHIJKLMNOPQRSTUVWXYZ 
 Ringer: I love Ringer. I find her to be a much more complex heroine than Cassie. However I do appreciate the fact that both of the girls are very different and fully realized people. (view spoiler)[ That scene with Ben, where she's debating drinking a capfull of antifreeze because she thinks the 12th system will protect her and it will abort her baby. O man. That was a heart breaking scene. Bleak but beautiful due to Ben's trust and devotion to her. (hide spoiler)] 
 Cassie and Evan: Meh. I didn't really care much for their scenes in this book. I loved them in The 5th Wave and The Infinite Sea but I just didn't like them so much here. Cassie was just getting on my nerves. Evan was barely there. (view spoiler)[So Cassie dies in the end to blow up the mother ship! That was such a beautifully bleak moment as well. It was symbolic of humanity enduring but still... I hate it when the main character gets killed off. :( (hide spoiler)] 
 Ben: I really liked Ben through out the entire series but in The Last Star he serves a very important purpose. I think he is the last glimmer of hope. If humanity ever has a chance to recover, it will be because of people like Ben Parish. 
 That ending: It ended. That's the best way to describe it. Was everything back to normal in the end? HELL TO THE NO! But it felt like a real ending. Like in The 5th Wave and The Infinite Sea our protagonists are going to to the best they can for as long as they can. That's really the best anyone can hope for.