Absolutely fantastic tool. It's not limited to ads (though it handles them wonderfully), if play around with the element picker a bit you can easily remove a good chunk of the cruft that corporations seem to love plastering on their products these days. Get good at writing the filters by hand and you can do /magical/ things. I love the feeling of not being subject to every whim of some marketing executive. Take control over your experience on the internet! It's fun!

Tip for new users: though the defaults are very good, make sure to check the "Filter Lists" tab in the dashboard and see if there is anything else you'd like to enable- I recommend some of the "Annoyances" lists.