I can not express how useful this add-on has been to me. It is phenomenal to be able to group tabs according to what I'm working on and to swap between groups as needed. It's great for pausing a project and returning to it later.
So very, very good. I keep wanting to recommend it to friends who have 100 tabs open, but most are running chrome and it doesn't seem to have a similar add-on. Their loss!
