It seems pretty decent, once one understands at least some basics. However, although I can't comment on long use data loss, which other users obviously experienced, since I am only using it for a few days now, for me, I have two main problems with this add-on:
(1) If Firefox is *not* open and I click on a link in another app which opens Firefox, then Firefox is opened *but* the link is not followed. I have to go back to the app and click the link again after FF is open. This sucks.
(2) The context menu of the "tabs" in the side bar to not offer any tab context menu items but *only* custom "Simple Tab Groups" items. This defeats the purpose of the side bar for me, which would be that I could turn off the main tab bar. But then I do not have a tab context menu anymore with this add-on. So, as a work-around I am using the "Tree Style Tab" add-on in the side bar and for now the "Simple Tab Groups" in the tool bar.

I searched for it and was happy using it - until it repeadetly erased all saved tabs after some weeks of using it without problems. 2 times. Which makes my work life really crappy.

Lost tabs of days of work
Backup doesn't work as all groups I saved are empty !
What's the f*** with your extension why it hide the tabs !
So after firefox restart all are lost without any reason !

I've been using this add-on for about a year now, and while it's hit some typical development roadbumps, it is a fundamental part of my browsing experience. It is simply a fantastic tool for organizing the hundreds of tabs I have at any given time, and backing them up as bookmarks is a fantastic bonus feature. I think there's a reason this add-on has been designated as "recommended" by Mozilla/Firefox - I wouldn't be surprised at all if they were looking at bringing the features of this add-on into the main FF codebase. IT'S THAT GOOD, REALLY!

Thanks to this half assed extension I just lost over 100 tabs I had opened in my browser. Thank you.

Can't live without this anymore. Minimal yet very configurable.

Absolutely love this add-on! Any chance you can port it to Microsoft Edge Chromium? My company is going to blacklist Firefox in the summer :'(

Awesome! The best addon for productivity, does exactly what I wanted.

Lost some of my open tabs when played around with the plugin right after installation. Besides, that everything works just perfect for me. The integration of Multi-Account Containers is very neat. The STG plugin is just super helpful when you hassle with dozens of tabs

must install this.

Great add-on. Thanks for your time.