Addendum 2: So, I got a new computer and I used this extensions sync feature. Regrettably, in the process of doing so my site lists for my containers were nuked. This has caused more headache for me than the privacy benefits are worth.

I'm finally uninstalling this extension.

Addendum: I didn't realize briefly turning this extension off would wipe out all my containers and settings for this extension. I turned it off for a bit since my Dad might need to use my browser for a bit and I didn't want him to be hassled by my extensions. So, I wish there had been a warning about this or a way to backup my containers and settings I've created over the past few months.

Original Review: Something I never knew I needed. Lots of user-friendly options such as being able to set a website to only ever be opened in one container. This means I don't have to first open a tab in that specific container then go to that website. Also, it's handy in preventing every social media in existence from tracking me since I've put each of them in their own container. Thank you Mozilla!