UPDATE: The plugin has been completely unusable for several months now. The problem is that it constantly asks for your username and password, there is no way to save them, and entering them just results in another prompt.

It's working relatively well so far, but there are a couple problems:
1. We're forced to use Firefox's builtin tracking protection (privacy.trackingprotection.pbmode.enabled). I really dislike this, because I prefer to use PrivacyBadger to dynamically block trackers. This should be user-configurable.
2. I'm prompted to relogin every time I open a Private Window. I would much prefer for it to work seamlessly, remembering my credentials the way it normally does.