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:
It does an excellent job on mildewed wood such as decks and deck furniture without using chemical mode which is the only weak link in an otherwise strong chain. Unfortunately, the only effective chemical solution is chlorine which acts more or less on its own but cannot be used with this machine. Safe cleaners, such as Simple Green are no more effective than when used without them. Other than that, it's a great product.
Answer:
Positive