Rated 5 out of 5 stars
@Alexander, So it's as useful as a UserScript, which you apparently think is a bad thing. Big deal. We use it because we can't be bothered with UserScript. I doubt that some or even many of us even know what that is.
Just because it lacks some features that you think it should have (I'll concede that a multiple-tab integration would be an improvement, but nothing else you've said makes sense), doesn't mean it's a bad add-on or that other people shouldn't love it.