It's of interest only in a "religious" sense. Young children will probably get bored and older people may find the steep, narrow stairways too difficult to climb. You can't get any tea/coffee there either.
The reception/ticket area is tiny and crowded with people arriving, leaving, trying to get their coats on/off, buying tickets, getting their bags out of a trunk where they have to be stashed, and trying to buy postcards. It put me off at the start.
It has to be said though, the church in the attic is admirable.