I am giving two stars and not one because the idea is actually superb - it if worked. I have installed the add-on, re-started firefox and yet I do neither get a blue line nor a blue writing when opening facebook. And unfortunately I do not understand why. Having a look at my preferences, it says that the Facebook Container is activated and manages all tabs. Even deleting the add-on and going through the whole process once or twice more did not change anything.
I do not use any other container add-on - only if there is something pre-installed that I do not know of.

According to the comments listed herein, the add-on seems to work for most users. But I also figured out that I am not the only one having problems - which makes me optimistic that there might be a bug just needing a fix (:

Who can help?

DOESN'T WORK! I installed the add-on per instructions, checked for updates to the add-on (I'd just restarted my Dell laptop running Windows 10 Pro to update to the latest version of Firefox - 59.0.1), and restarted Firefox itself just for good measure. I also checked the help section and the add-on is, in fact, enabled (the only options I have are Disable or Remove). I logged into Facebook again and the word "Facebook" does not appear in blue, nor is there a blue stripe on the tab like there is in the pictures of it working correctly. I don't know what else to try to get the extension to work. :(

I have a lot of the built-in privacy settings in Firefox already enabled, but I haven't made any particularly weird or complex modifications. This is the only add-on I have installed, so I don't think it's poorly interacting with anything else I have going on.

Love the idea - if it actually did anything! I'm so bummed I created a Mozilla account just so I could write this review! (Also, when you go to the Extensions Manager and click on "More" in the description of the extension, at the very bottom it says "If you come across any issues with this extension, please let us know by filing an issue here", but there isn't a link to anywhere to report issues, so that's also why I'm having to do this in a public review.)

Ok

Really great idea. Any plans on making one for all the Google sites too?

Lets protect the privacy :).

This is a great idea!

Any plans for a Google Container plugin as well?

Firefox forever