The uninstall secret is Rated 5 out of 5 stars

Where you Select from your search engines dropdown menu at the bottom | Select Manage Search engines | click one you want | click remove button et viola!

If you download this add-on , you will see the installer here is an XML file not an XPI file like other add-on's, in essence it's a Search Engine, so you deal with it in your Search Engines.

Not sure why it's even listed as an add-on but, what am I to know, it works, and you can also uninstall it just like I said.

Easy access to one of my essentials Rated 5 out of 5 stars

This search engine implementation of DownForEveryoneOrJustMe is one of my essentials. As I tool around the interwebs, doing research or just for the heqq of it, I find interesting references. When my DNS provider, OpenDNS, says the site is not available, it is generally not. this extension is my easy double check.

Works great for me Rated 5 out of 5 stars

Works great for me, I can check whether it's me or the world

Rated 2 out of 5 stars

This add on adds a "down for everyone" search option to the standard search box in firefox. If you don't use this (say if you have google toolbar) and prefer it to be hidden, then this is not for you.
I tried moving the search box to a new toolbar so that I could hide it and bring it up only when I needed it. Unfortunately the toolbar appears everytime I start firefox.
The final negative point is that I cannot find a means to uninstall this add-on.
Other than these issues, the add-on works fine. I will be continuing to look for a way to remove it though.