Couldn't live without it... Rated 5 out of 5 stars
...well, not literally, of course - it's only software!
But like many others*, I can't work effectively without a myriad number of tabs ready at the click of the mouse, neatly organised into tab groups (or project headings/research areas/whatever). Helps keeps topics at the forefront of my mind.
This add-on is simply superb.
Except that it does have a few bugs (what doesn't?), which are becoming more apparent with each Firefox version (e.g. see spot-on comment by Martin, 17-12-2012).
Initially, I thought it was due to the sheer number of tabs I had open (250-ish), and perhaps the code was coming up against some internal limits, but Firefox will apparently continue to open tabs whilst there is available RAM & processing power.
It really could do with updating and I am glad to read that user One Ken Thomas may pick it up. I am also perturbed to hear the original author is having problems.
Best wishes to them both though, wherever they are.
*It doesn't seem to suit my dear wife though, who, on the few occasions she finds herself sat at the pc under my user account rather than hers, will utter the familiar wail "WTF...why on earth do you need all these hundreds of tabs open for...?".
Best to ask her just to switch to her account and make her a cup of tea...:-)