I thought the setup was OK. The first 4 waves were understandable, and the first half of the book was pretty creepy. But the instalove and the weird plan for the 5th wave brought down my enjoyment quite a bit. Also, Sammy annoyed me quite a bit but fortunately it wasn't his PoV too much so I could ignore that for the most part. And Cassie, well, I don't think that she was written very well. First of all, she talks about her former crush way too much for the situation she's in (talking with her friend about having sex right before the end of the world because it's the end? Really? She doesn't have more important things to focus on?), and she completely ignores her instincts regarding Evan, even though she's pretty sure he's an alien. And the instalove! Made her characterization even worse. She's supposed to be at least somewhat decent at having survival skills seeing as how she survived that long but wow, I don't see it at all. How is Evan too in love with Cassie, without even ever have talked to her, that he can't stand to kill her? How can Cassie ignore all the things that aliens have done to other people just because he's attractive?Finally, I'm not a fan of the PoV change but I would have liked it a lot more if they had the character's name at the start of the chapter or something to make it clear whose PoV I was reading. Even in the case where (obvious as it was) Yancey might not have wanted to reveal Evan right away, he could have used his title as shooter or something else to conceal his identity.