This add-on alone is a reason to use Firefox

Months later, this remains an incredible tool that is hamstrung by severe bugs.

For example: you can't sync containers between Windows and Linux. You can sync containers created in Firefox running on Linux with other Linux installations, and you can sync containers created in Firefox running on Windows with other Windows installations. But sync across OSes, and you'll wind up with two independent sets of containers synced to the same account.

Another example: the extension frequently spams dozens if not hundreds of additional containers. If my list looks like "Facebook / Google / Shopping", then one day I'll have "Facebook / Facebook / Google / Facebook / Google / Facebook / Facebook / Facebook / Facebook / Facebook / Shopping / Facebook / Google / Google / Google / etc". Because there's no way to clear out your sync data, the only way to fix this is to completely delete and re-create your Firefox sync account or trigger a password reset.

Another example: When you win a badge ("hooray! You just opened 100 tabs!"), it stops using containers. Eventually you'll click on the extension to find out why the heck it stopped working. That's when you find out that alerting you to whatever stupid "award" you've won is more important than actually doing the one job it has.

This has the potential to be a game changer, but it's just a half-baked pile of garbage.

Really usefull extension, I use it every day to separate the activitites I do on internet. The only feature I really miss here is containers ordering. Now I have 8 containers and they seem to be in different order every day, due to synchronization between computers. When I open new tab in specific container, I always have to search, where it is today ...

It's pretty useful, but some of the wanted uses of the technology lead to problems with wanting to have universal settings for some things. There's also at LEAST one pretty significant bug, that it still has: bug 1670278 in Bugzilla.

I use this extension every day! As both a user and a developer, it's soooo helpful being able to keep different accounts logged in on different containers! And it's easy to keep facebook, google, amazon, etc in their own containers so they can't track your other activity. Syncing containers across browsers is awesome too.

The only thing that really bugs me is I'd like to be able to rearrange the sort order of my containers in the menu.