This is add-on is not only amazing, it is essential.
I use it for two reasons:
1. The massive privacy boost.
2. The ability to separate my work and private life. I also use containers for finance and shopping.
Before this add-on I would have to either use a second browser and log-in to different accounts in private mode.
I love this add-on.

the main reason why I prefer Firefox to any other browser

Having separate cookies for each container is an absolute godsend!
The thing I really miss is, that you aren't able to set containers in bookmarks, that's why I deducted a star.

On YouTube, I have a container for each of my channels, so I don't have to switch accounts constantly, and each container is saved as a separate bookmark, so I can access that channel easily.

For the time being I installed a separate extension to solve this, but imho, this should definitely be solved in this extension, since this is a very basic/common request I would imagine.
https://addons.mozilla.org/en-US/firefox/addon/container_bookmarks/

This is very useful. Thanks for building it.

This add-on is simply game changing! Containers are an essential part of my daily workflow and now this makes it twice as fast!

The one thing holding me back from giving 5 stars is PLEASE ADD AN EXPORT BUTTON 😵 Being able to sort and reorder the containers is REALLY nice but useless if the Firefox settings don't follow it. This means having to recreate the Firefox settings' containers before syncing the extension (which will probably break everything) so an import/export feature would make managing your list of sites much less a headache! 😁😁

Another feature I would like to request: Why not allow star notation for domains? Lots of other plugins allow me to add any google site with *.google.com for example. Includes every service for that domain.

Cool app. The only problem I have is duplication of containers on firefox updates. Not every update though.

It will open links to other websites into the same container if clicked on. It would be nice to have an option to disable this