If your requirement is that you want to be able to block a site and all it's pages entirely (e.g. example.com and example.com/a and example.com/b) I guess this works.

If -- like me -- your requirement is that you want to block the primary domain example.com but access links on same domain e.g. example.com/a/link/here.html it's unlikely to work, at least not without an enormous amount of frustration.

Also, the "save" button in the options need to be made much more visible.

It's pretty good, but a button to just remove the blocked site without the need of a master password defeats the ENTIRE purpose of it. Just makes accessing the site... 3 seconds longer for that initial attempt.

It loads the url before showing the "Restricted access" page, so it only visually blocks loading the page. I want something that never loads the page in the first place..