It used to work well. Now that it's been "updated" to automatically detect logins, it no longer supports Outlook/Hotmail. If I log off and back on, it's there briefly, but then disappears and won't return.

Pros: It can handle Multiple Google Accounts well. (Previously X-notifier(not Neo) needs re-login to the other Google account.)
Cons: It can not keep accounts information. (Previously X-notifier(not Neo) can keep them.) Accounts information on the dashboard and the right click menu of the icon disappear automatically every time. I guess this is a side effect of Neo's automatic login detection. So, I still need to use X-Notifier(not Neo) to keep my account settings.
Conclusion: Neo has not yet been able to become a successor to X-Notifier.

No tiene opción para Yandex Mail.

No me reconoce el email aol.com. Tanto para gmail con varias cuentas, y yahoo de lujo.

This add-on is not being updated and it barely works. It will only check one Gmail account, and you can't even force it to check another one. You have to uncheck everything and only check that one, and then it probably won't check it. This used to be such a great little tool, but now it's almost useless.

comprehensive functionality
very fast support

It works many times better than X-notifier.

It does not reset after opening Gmail, and deleting mails....no options other then check interval????

Le quitaron muchas opciones del X-notifier que lo hacían bueno

Better than X-notifier

Would be nice if containers would be supported (Google Container addon)

It works just fine with 7 Gmail accounts. The only feature that is missing is to reset the counter after a specific Gmail account opens and the mail has been read. It has to be done manually by pressing the refresh button.