Just demoed it on my dev board, works fantastically. It does a great job, I love how you can toggle the filter off from the settings, as well as have words replace to other words instead of just being ****.
Not to mention, the prefix option seems pretty nifty, not that I've tried it out myself (yet).
For these features, it does a pretty excellent job.
I like this, but my problem is what if you have other things in the censorship. Things that you want censored without the user's choice. If I use this addon, users would have the choice to uncensor those as well. Would it not be better to create a separate censorship for this add-on ? Just so it's easy for admins to let users control the censor ship of profanity only.