Rated 5 out of 5 stars

Haters are completely messed up in their opinions. I'd say to every Firefox user to give it a try. Really nice, works great, and the best I've found here in Mozilla add-ons.
And by the way, if you want to block access of certain content for children, there are TONS of other programs to do this. This extension was probably developed to help preventing installation of malware, and does this greatly.