The Good:
- seems to be doing its job
(though FF always still manages to use many 100's of MB and multiple instances of FF
for - I think - installed add-ons, Gmail and YT etc...but prob. Mozilla's fault)
- good extra features,
like only whitelist a particular tab or its whole domain name

The Bad:
- Youtube tabs that are reloaded,
are loading the mobile ("m.youtube[...]") version.
Really annoying!

The Ugly:
- nothing important really.
Maybe the icon. On/off button prob. not the best choice.