Rated 4 out of 5 stars

Can't seem to update my older review to let's add a couple of points here:

+ The ability to toggle a tab between private and regular is great!

+ Quick response from the developer fixing the missing favicons bug.

- Still wishing pinned private tabs would remain across sessions and open with their initial URL.

This review is for a previous version of the add-on (0.2.0). 

Rated 4 out of 5 stars

First thing's first: after a morning spent debugging the issue, I found this extension kills the site icons from all browser tabs except internal ones (like Options and Add-ons) on Firefox 50.

The basic functionality is nice. No need to tie a temporary session to a whole another window. It would be nice to be able to pin a private tab with a starting URL so that it would remain across sessions.

This review is for a previous version of the add-on (0.1.9.1). 

See https://github.com/Infocatcher/Private_Tab/issues/224
Fixed version already released, but not yet reviewed:
https://addons.mozilla.org/addon/private-tab/versions/0.2.0