I really like this feature; and a big reason I'm using Firefox as my default browser now.
Although one thing that I've noticed is that [in every device that I use Firefox browser on] I have to create all the containers over again--This is with signing in to Firefox browser and syncing... (Maybe it's a Bug that needs squishing...)
I'd definitely recommend this add-on feature to anyone who is concerned about their online privacy and to help avoid all of those malicious trackers and browser finger-printers that are seemingly everywhere on the internet these days. 5/5
Thank-you Firefox Team!! :)