Rated 1 out of 5 stars

This is one of the WORST user agent switcher add-ons that there is. There is NO way for you to put a button for this add-on anywhere (that is IF it even has one at ALL). There's NO way for you to turn the add-on ON or OFF when YOU want to. (DISABLING an add-on DOESN'T count). IF BOTH of these problems ever get fixed, this will be a good add-on, but right now, just use this "Override User Agent" instead.
http://addons.mozilla.org/en-US/firefox/addon/override-user-agent/