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:
Neither the salt mill or pepper grinder work well. It takes forever to get salt and pepper from the squeezing of the handles together and still not an adequate amount. Perhaps the blades that crunch the S&P are not sharp enough? Very disappointed in product.
Answer:
Negative