basic idea is good

but compared to tab groups as of FF < 5.4 it totally fails in usability
- takes too long to add tab, this must be on tab of tab context (right mouse)
- too fuzzy to switch, difficult to check tab list without loading

in reality I've lost multiple times all groups by opening them in a second FF window... so stopped suing it, and prefer (I'm forced to) to track tabs in a notes taking app

doesnt work with more than one monitor.
It will hose all your tabs.

Incredibly slow. Takes about 10 minutes load 20 windows in a tab group. Makes switching work contexts impossible.

Unfortunately, as soon as I select "import" from the addon menu, Firefox crashes :-(

This add-on has potential with some more development.
Cons: Very difficult to move tab from one group to another. Would have though you could have moved tab around in edit, but cannot see how you can. Slows Firefox when loading a group that you have many tabs in group. It seems to load each one before response is back to normal. No Drag and Drop. Does not show the favicon in edit or quick list view. Open a new window and pinned tabs are not included.
Pros: Nice edit layout. Works with 57.x

This interface is unusable. I cannot figure out how to move my tabs into different tab groups, every time I try to switch tab groups it seems to generate another tab group for just the one tab. Needs way better tab management if it's going to handle my tab load on over 75 open tabs at any given time.

There are a lot of errors in the extension

1) Do not save the name of current tabs group where FF is closing!!!
2) When i use SWITCH, other tabs closing (if i listen music on youtube.com & switch to other group tab, youtube closing, no music)