Yes it's strict - enough to break most web pages. If that doesn't bother you perhaps getting a prompt on every single web site you visit might. It bothered me. I found it far too invasive to be practical.

It's very good

Whitelisting doesn't seem to work for onedrive and office online

Add-on is very useful for blocking pop-ups and works extremely well at catching them, however I have an issue where when I receive a request and allow it, Firefox itself notices a pop-up and blocks it so I end up closing the notif for that a lot, if I set Firefox to allow pop-ups then when I allow the add-ons request I get a duplicate tab for the pop-up, I modified my Firefox browser a lot like the config and I have a lot of other add-ons so I assume I might have changed something that made this happen so take this with a grain of salt.