It works - for the most part. I did a test Google ("bop top" if you want to recreate my test) and didn't see as many of the sites with favicons next to them as I hoped - I saw about a 60% success rate. Which is great, to me, because I just wanted to do a quick scan of my sources, which I can with this extension, though it doesn't always work. Websites without favicons still displayed the little default icon that Firefox is, so this isn't a problem with the extension. I'm going to be using this extension until it's deprecated and incompatible with Firefox.