Worked for a day and now shows I have 0 mails even when I have a lot. Tried uninstalling and reinstalling but it didn't help.

Kompletter Mist.

didn't work, try Notifier for Inbox, it worked easily Good Luck

Has annoying ads that pop up above all other windows in the bottom right corner of the screen, while using the browser. You don't even have to be using the add on, just browsing as usual, and you get his ads. There is no option to turn them off either.
1 star until this changes, otherwise it would have had a decent rating. It's a simple add on.

This add-on just didn't work. I was signed into both my Gmail & Yahoo account and sent numerous emails back & forth between the 2 and it didn't acknowledge even one email. Even when I clicked the "recheck all emails" option nothing happened.

Doesn't work properly!

Doesn't work, as far as I can tell

Can't hear the warning sound when I get mail. Keeps reminding me of old mail from years ago.