Okay, so I like to be suprised, and very often when I'm suprised by a book it results in 4/5 stars. 
 It's the same with The Thousandth Floor. 
 At first it was hard for me to picture the world. The worldbuilding is fantastic, but it's hard to imagine a tower with 1000 floors where you also have "streets" and "outside" while you're actually inside. 
 After 50% I was totally into the world and also into the characters. I love how everything comes together near the ending of the book. 
 I really thought that I was going to give this book 5 stars, but when I compare it to my other 5-star books, I just couldn't. The fact that I didn't give the book 5 stars, is because some of the characters seem really "shallow", the way they only care about their own feelings and possessions. I like Eris, Riley, Watt and Cord. But the other characters are only thinking about themselves (a little bit too much), wich resulted in the tragic ending of this first book. 
 I'm really curious about the next part, because this book feels like reading a television series!