Rated 4 out of 5 stars
Loved this add-on when I first found it, but now I've noticed a couple of issues:
#1) After installing FF 29.0.1, the icon to access Tab Grenade has disappeared completely. This is obviously a major issue, as the add-on is now unusable.
#2) There seems to be no way to get rid of old history for tabs saved. So, apparently, it just keeps storing old tab groups forever. Would be nice to limit the length of time they're saved. Minor issue, but would be handy.
Other than the above two items, Tab Grenade is quite useful.