In brief:

In my opinion, this add-on looks trustworthy and well thought out.

Works as advertised for my use case, which involves simple, always-on blocking of a few domains.


Details:

This plug-in seems to be good quality and privacy-conscious "under the hood". There are a couple of other add-ons that advertise a similar functionality, but I consider their dedication to privacy to be questionable.

The interface of this add-on is a bit unusual-looking/non-polished/non-intuitive. But I expect to find something that is not quite right yet, given the "Experimental" status.