it does about what you would expect, though there are some serious UX issues I wouldn't have expected from an "official" plug-in. Particularly in regard to the "Always open in this container" feature. You would think after so many complaints/github-issues like #1999 (https://github.com/mozilla/multi-account-containers/issues/1999) about it being hard to undo, they would've done something. Can't in good faith rate this five stars until they fix this, but it's still a decent add-on either way.