Instruct: Classify an Amazon review as either positive or negative.
Query: The best Harry Potter book yet!

This is the best Harry Potter book yet. Each and every one of its 870 pages kept my nose in the book for hours on end (I know, it's a long book, but I read it in seven days; I couldn't tear my eyes away.). This book has it all: suspense, action, friendship, irony, many unexpected plot twists, and even a little romance.