Rated 4 out of 5 stars

It's a nice RSS-feeder but it doesn't supported password-protected RSS feeds.

This review is for a previous version of the add-on (2.3.0). 

Brief relies on Firefox being already logged in. There's no special support for remembering passwords or using the Firefox password store. I've created a feature request on Github for this (https://github.com/ancestorak/brief/issues/239).