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:
I bought a couple of these for my sons. They love to play with them, but after only a few hours of use, the batteries are dead! This could get really expensive considering the batteries are about $3 each. Also, one thing that gets very irritating is the shaking of the PET that has to be done when you get a "virus". Very annoying!
Answer:
Negative