Rated 4 out of 5 stars

The must have theme for all elementary OS users. IT looks just perfect. I am not sure if I like, that it always shows the forward button, but I can live with it.
The sad thing: it breaks the notifications style. Notifications look really ugly and have a random size (based on the content). This happens, since ubuntu doesn't provide a libnotify implementation with feedback. I hope elementary OS will get a new default notification library which will support it, so firefox uses system notifications.

This review is for a previous version of the add-on (2.1). 

The forward button is a part of the elementary UI design for a web browser. I understand that Firefox only shows it when there is a page to go forward to, but I've also been thinking about removing it. About the notifications, this theme doesn't modify the Firefox default notifications (apart from some icons, eventually), so I can't really understand why you say "it breaks the notification style". Maybe I'm missing something.