I do - kind of. Since I don't have Firefox set to reopen the last batch of tabs I had opened the last time I was using it, Panorama is kind of useless in my case, since I would mainly use it to keep tabs grouped by content, and it would be a chore to redo the grouping at each restart. Still, it comes in handy to keep reddit/hn on one group and work related stuff on another groups and quickly switch between the two by doing Ctrl - Shift - ~. A big optimization was to set browser.panorama.animate_zoom to false in about:config. That animation was killing the flow in my case.