Rated 3 out of 5 stars
Great add-on but unfortunately still very buggy at present.
I like to combine TabGroups Manager with Tab Mix Plus and with Tree Style Tab. All 3 add-ons give unique and powerfull features which you cannot miss once you have taken the time to learn how to setup and use them.
BUT there are many bugs left and even showing up once you update FF or some add-ons since apparently the developpers do not take care of what the other developpers are doing. I know it must not be easy to coordinate but it remains a big problem for the users.
After I had during months 2 empty tabs appearing again when I used to close the last tab, I finally found the latest version 2009.06.19.01 which seems to correct this bug related to Tab Mix Plus.
I don't understand why the updates are not proposed automatically and why there's absolutely no mention of it on the main page. So one have to dig deeper and explore the link at the extreme bottom of the page 'View Older Versions' in order to actually get the latest ones... Not good at all !!
Besides I recently updated (automatically as usual) various add-ons and now every time I reopen FF I have 2 windows instead of only one (which was left when I closed it the previous time). Where is the bug ?? Always the same problem since it happens only with combined use of the 3 add-ons I mentioned above...
And last but not least I can confirm what buergi wrote because I experience the same type of problems again and again. The saving of the sessions / hibernated groups is utterly unreliable !!!
I wish the developpers stay at work to reach an adequate quality of their apps.