I am supposed to look for a pornography-blocking program for all of our home's computers. I have had some experience with these in the past (my school had one) and all i know is: I hated it. It blocked many harmless sites, which was very frustrating.
So, when looking for a filter, I want to make sure it won't overblock, and I want to make sure that it won't slow my computer down while running in the background. If the filter does its job and just blocks pornography, I don't care about it, but if it slows my computer down and blocks sites that I know are harmless, I will hate it.
oh, and by the way, I know that many of these programs have features that allow someone to look at where other users have been on the internet, I neither need or want those features.
i like google custom search, though it's not really an internet filter. it's google's application, so there is no overhead on my side. i just use it to filter out wikipedia and slashdot entries, though. a while back, in one of my schools, we used "st.bernard" internet filter. it didn't suck THAT bad... and you got to choose what you wanted blocked, porn OR spam.