It's free and decent for keeping an eye on your credit. They give you a fako score which can vary widely from your fico (or can be quite similar). Don't give them any money.
It's a pretty decent tool. I have been using it for a few years and have never been asked to pay anything to be able to use any of the features. Update your score once every month and it should provide you with a good indicator of your credit score. I would recommend it.
I've just made use of the free annual report that the credit reporting agencies are required to provide upon request once per year. It doesn't have any tools associated with it, though.