It does what it says, and nothing more. It's basically an MVP that fills the name: it allows you to enable and disable extensions and themes.

Unfortunately it also doesn't have much to make me confident it's secure to use. The developer account links to a betting site, and I can't find any links to the source code.

I'd love to see this extension developed further. The existing UI is minimal to point of being non-existent. There are no icons or any info besides the name, type, and an on/off toggle. Themes and extensions are mixed together and for some reason themes are labeled as "plugins".

Unfortunately this is still the best (working) extension manager I've found for Firefox so hopefully it will get addtional features. Features like links to plugin settings, and categories/groups would go a long way toward making similar to the dozens of extension managers available for Chrome.