Given reviews from Amazon, classify those review based on their content into two classes: Negative or Positive.

Let me give you an example: I've read this book with much expectation, it was very boring all through out the book
The answer to this example can be: Negative
Here is why: Review writer does not like the book because it was boring, therefore it is a negative review.

OK. solve this:
After reading this book, I felt guilty for having purchased it, because that contributed to its best-seller status. (Oops, maybe not; the way it works now, it was a bestseller the day it hit ths stores.) But it is sad to think of all the aspiring writers who struggle to get a publisher's attention for their worthy efforts, while this strangely hollow piece waltzed its way to bestseller status. Some editor should have thrown cold water on this potboiler.
Answer:
Negative