I am loving #Firefox profiles, actually. Container Tabs were very nice to use, but this is even better. I have an icon for "Work Firefox" that opens an instance with my work profile loaded, and it assigns a class name, so my window manager differentiates.
If you delete a bookmark/folder in #Firefox, you can Undo from the Bookmark Manager if you haven't closed Firefox yet! Whew. They changed where Delete and Add are in the context menus a while ago and I haven't gotten used to either place yet.
I am however, very annoyed that they shrunk the preview size of my top sites icons on the new tab page. The about:config property has been made obsolete as well. Anyone have any user chrome CSS fixes? #firefox