Moziller keeps advertising the tab groups at each update. This seems like a neat idea, but I'm not sure it's any easier or better than just dragging tabs onto the desktop, where they become new windows. You can switch between "groups" faster, when you just click on another window, down on the toolbar. Or whatever the short-cut, window-scrolling method is.
I like to keep my background music in a separate window, so I can close the window I'm actively using, without accidentally killing the streaming content. Tab groups do not work this way. In fact, there's very little indication that other groups are lurking back there.
