Kudos Rated 4 out of 5 stars
I, too, was perturbed with Mozilla for the same reason as the developer: updates performed behind the user's back without any prior notification. This annoying practice occurred not only with Firefox but with Thunderbird and SeaMonkey as well. Add-on Update Checker 1.3 perfectly resolves the problem for all three programs.
I heartily agree with the previous reviewers: this add-on splendidly fills the void left by the demise of Update Notifier. While it is puzzling how the add-on is hosted on a Mozilla.org web site with a disclaimer that "This add-on has not been reviewed by Mozilla," many thanks are in order to the developer for a job well done!