Rated 2 out of 5 stars

Someone did say already FF does it's own add-on checking, but note FF doesn't really display an indicator after you missed its initial popup (though it does show a dialog to install updates on FF run later). This extension was nice to have but it not being updated for FF betas -- which I feel is the most important time you need it because you want to find when incompatible extensions are updated ASAP -- makes it obsolete and useless now.