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?

Thanks for making this, but I have no way to use the “container” on my iPad or iPhone. I do have it on my laptop, but with my disability, I can’t always use just the laptop.

Na hora de fazer login em sites pelo Facebook, o plugin atrapalha bastante.

Warum gibt es das nicht für Android? 5 Punkte gibt es, wenn es auvh für diese Plattform verfügbar ist.

2 stars because it is not on Firefox android. Love this and when it is on the android version i will give this 5 stars as it deserves.

It was easy to use.

Nice Addon, but please mozilla fix the white screen flashes on tab switching and on new page loading