Really a great extension! Helps me to monitor many things online. Recently after the last update however, I've noticed that any time I connect to a VPN the notifications go haywire, notifying me that every single site has changed though they haven't. I have to subtract a star for the fact that I have to disable my vpn to use it.

The "Auto-hide notification popup after: " Option doesn't work anymore... it will disappear after 20 seconds, doesn't matter which time you have set.
Also changing the "dom.webnotifications.requireinteraction.enabled" in the about:config to true didn't help.

And somehow the email service doesn't work as well for me.. tried to send it to my gmail but no notification yet.

If there are many open tabs, it will be loaded into the current tab instead of the sticky window.

Periodically and systematically it loses or ruins the watch list, even so I continued using this extension, but now the number of monitored pages is limited to 20 for free accounts, which makes it completely useless for me. I uninstalled it, there are other good free alternatives out there.

Periódicamente y de forma sistemática pierde o arruina la lista de vigilancia, aun así continué usando esta extensión, pero ahora el número de páginas monitoreadas se limita a 20 para cuentas gratuitas, lo que la hace completamente inútil para mí. La desinstalé, ya que hay otras buenas alternativas gratuitas por ahí.

UPDATE:
Well, now I give this 3 star because now they implement a server to backup the watchlist and rise the number of monitored pages for free accounts to 25.

Addon works well, but doesn't work at all with tracking protection enabled which is weird. It's closed source, too.