Using the tool is incredibly easy, all you need to do is drag the Readability button to your web browser tool bar.
I've tried it on several websites and it works really well, I can see it being the perfect weapon when reading heaps of text on screen, and a great alternative to printing something that you may not want to keep.
Below is a video showing you how to use Readability.
If you're not sold on the idea - just look at the before and after I tried using a Department of Health news page.
Click on the images to make them larger.