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 love having this thermometer. We have three kids and one is an infant.I got rid of my pile of cheap thermometers! I don't have to second guess the reading like I did with the cheap ones. If you have an infant, you will need a rectal probe. I ended up buying that and switch them out depending on which kid we need to check. It's easy to switch out and I recommend spending the money to have that peace of mind.
Answer:
Positive