It's a useful addition to better oral health. It takes a few tries to keep the water from squirting everywhere, haha. Generally easy to use once you get the idea of how it works. If you have sensitive teeth, adding warm water is a good thing and a couple of ounces of hydrogen peroxide is has beneifits for a clean mouth.
I received my Waterpik® WP-100 as a gift from a co-worker as part of our Elfster gift exchange. Requested as a gift since I was going to purchase for myself. Very easy to use. My teeth and mouth feels great after each use.