Excellent..but Rated 4 out of 5 stars
Super addon and perfect for customizing the internet and enabling new features.
It does slow browsing down on some sites. There's a few blogspot sites which take about 20 seconds longer to fully load when GM is enabled. I've added a few blogger, blogspot wildcards to the global excludes but the only thing which speeds up those sites is disabling the addon completely, then restarting FF. If anyone knows of any other workarounds, that would be great.