It does exactly as the title claims. So far works perfectly, more customization would be appreciated but it is simple and tidy and that's okay.

No 5 stars yet because a perfect score would imply a perfect add-on. The borders aren't perfect, resizing is a bit finicky, size changes aren't saved after minimizing the note. It would also be very nice to have an additional tab inside the note for per-site notes, with the option to view all notes made if it were to be added.

Despite these imperfections, it's still an add-on i'd definitely recommend for now.