Works great in theory, but not even remotely in practice. The addon doesn't remember my settings between tabs, which means that sometimes the addon doesn't active on tabs when I've turned it on, and is still active on tabs when I've turned it off.
Even worse than that, sometimes I'll change tab and it's seemingly just picked a palette all by itself. I set Midnight Lizard to "Apple Mint", only to open Youtube and inexplicably see it in "Sunset Sails".
My last problem is what everyone else mentions, in that it slows my Firefox to an absolute crawl. Both loading times and actions on the pages takes ages.