while normally it does its job, in my case it failed spectacularly when i needed it most. i had a power failure, and upon boot i find all of my tabs are wiped as usual thanks to firefox's abysmal handling of sessions. so i go to tab session manager to restore them, only to find that its extension database (alongside a few other extensions) was also wiped/corrupted, which means no tabs at all.

the extension could use some sort of cloud backup, on google drive or dropbox to store selected (or all) sessions online for quick retrieval in case firefox's unreliable database gets corrupted or wiped.