Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Characters lacked depth

The premise and setting of this book had so much potential that the characters did not live up to. Once the storyline moved back to the U.S., the story died. There was dialogue between characters that was hard to follow because it assumed we knew so much more about the characters' psyche than we actually did. I felt like NOTHING happened in the latter half of the book.