Good, but needs options Rated 4 out of 5 stars

There need to be options for how to change the text labels on private tabs. Perhaps even an option to use a special favicon.

REPLY: If I'm understanding you correctly, I'd just put them in anyways (change the userChrome.css yourself) and, if an extension messes it up, it messes it up. But I don't see why it wouldn't also mess up the blue underline.

Thanks for the workaround, anyways.

This review is for a previous version of the add-on (0.1.3.1-signed). 

You can found some styles for userChrome.css/Stylish here:
https://github.com/Infocatcher/Private_Tab#styles
(but currently I don't have style to change tab labels, only example for icon available)

It's very hard to implement customisable appearance in case of many tab-reletad extensions and themes (e.g. there is at least 4 built-in themes: for WIndows classic and Aero, for Linux and for Mac OS). Thats why only UserStyles available – some of them should be corrected for some themes.