This addon is important because Mozilla has abandoned free and open web technologies.
They've deprecated Livemark RSS/Atom feed reading to be removed by Firefox 63. They are now going to be pushing Pocket, which is a proprietary technology that they purchased, with the belief that focusing all their efforts on that will get them beyond 5% overall browser marketshare.

As of August 2018, I've found this addon has stopped updating[0] for me. Similar behavior to how I found Foxish in Chrome to function years ago. I'll update my review as things change, but I'm close to abandoning Firefox altogether after 16 years of using it, since it was Phoenix. The only thing left are containers and the dedicated search bar.

UPDATE 10/17/18- all problems resolved. This is now better than Foxish ever was. Changed rating to 5 stars.

[0]https://i.imgur.com/8U43aY8.png