[userbinator]

If all it's doing is blocking "predefined domains", I wonder how it compares to doing that with a HOSTS file. The latter is non-browser-specific and works for all applications on the system.

[johnny22]

editing the hosts file requires admin privileges doesn't it? Doing it in the browser means it works for everybody that can launch arbitrary executables.

[killwhitey]

Worth mentioning that this setting is in Firefox for Android, which makes it much easier compared to rooting the phone.