Useful but limited Rated 4 out of 5 stars

This add-on is useful however I find that when I've already blocked some third-party sites it doesn't list them when a site calls for the. Many sites have seemed to "just not work" and it turned out I had blocked a domain, however Cookie Manager wasn't showing it in the list to unblock it.

Overall though it's nice to quickly block and unblock sites rather than trekking through the Tools menu.