I've been using this for some time, and I have to say it's made the web much easier on my eyes. I used to get headaches with all the bright white light some websites like to cram down people's throats. This works well, has minimal performance impact, and has multiple options so that even if a site has some breakage with one, you can pick another setting and still have nice black backgrounds and light text. I love this extension and it's a must have for me now.