I highly recommend The 5th Wave. 
 From The Monstrumologist to this -- Rick Yancey, make me a hard-core fanatic, why don't you? 
 If you don't kill all of us all at once, those who remain will not be weak. You are remaking us. 
 We are the clay, you are Michaelangelo. And we will be your masterpiece. 
 I cannot contain my happiness with The 5th Wave. It was a stellar alien book from no less than Rick Yancey! 
 Cassie is a very magnetic heroine, I cannot help but root for her. The determination and indomitable spirit was such a surprise. (But now that I thought about it, one of Yancey's strengths as an author is the ability to develop engaging and worship-worthy characters.) The stark contrast of Cassie's character to the hopeless world she lives in, it makes me want to cheer for her, that she will make it to the end. *fingers crossed* 
 So the moment that certified I was hooked? Zombie's character. When his POV was introduced, I didn't know who he was. Imagine my ecstasy when his true identity was revealed on his first chapter, I was giddy with excitement! Leave it to Yancey to stir things up in a major way. :D Smooth talker, this one - and the inappropriateness of it in a post-apocalyptic world was very funny. Heh. 
 Evan Walker. Even without his link to Cassie, his character would still shine. The shift between morality and mortality, as Cassie perceived him, was so addictive. Every scene that Evan's in was sweet, heartbreaking, I just want to capture each moment. *sigh* 
 Needless to say, the alien plot was gripping, the villain was hateful, the edge-of-your-seat element was electrifying. Woot! 
 With obvious strength in characters and decisive story flow, The 5th Wave deserves two thumbs up from an existing Rick Yancey fan like me. More alien conspiracy, please! 
 P.S. Me thinks this book will still be awesome even without the romance angle.