Has problems Rated 3 out of 5 stars
I've always said that security and privacy are a good thing... up until it interferes with your own access to content.
3 stars for effort. The addon is a good idea in theory.
This addon interferes with viewing content that is served from third-party hosting servers--both enterprise level, and discount alike), such as image hosting, flash media, and video streaming server hosting companies, to name a few, that won't serve the content without a receiving a referrer url from the site that is paying for the hosting to support their portal. This is typically to keep down bandwidth increases resulting from link proliferation due to other services (such as Google Search, for instance.)
This add-on interferes with a lot of sites on the web.If you are multimedia oriented, and spend much of your time looking at video, image sites (like Wallbase.cc), or listening to streaming music, then this add-on is not for you.
If you spend most of your time scanning news websites, reading articles, writing blogs, and doing research, then this add-on is probably a good idea for you, especially if your involved in controversy like 9/11 Truth, research into US banking and Wall Street frauds, and any other type of conspiracy or government cover-up studies.
* Update: The developer brings up a good point... the addon apparently allows you to "white-list" sites. I didn't check for that. :)
As any other privacy addon you have to whitelist what you want to happen, and you can do that with this addon too.
It's like saying NoScript and RequestPolicy are bad because they break websites out of the box, you have to configure them, this is true for Smart Referer too.