Cameron Skinner, Product Unit Manager (the guy who runs the product group), has a great post with a walkthrough of the test data generation tool. You can find it here:
He shows you exactly how to put this puppy to use. Go ahead and read the first 2 parts of the series as well to catch up on some of the other exciting functionality that you've missed.
So check it out! And definitely let me know your thoughts. If there is some functionality that is missing, I want to know so I can get it in there for you.