Bloodborne will score well because journalists know what fans expect. Even if it's not as good as Demon's Souls or Dark Souls, it'll probably receive better scores simply because it's the newest one, similar to what happened with Dark Souls 2.
I'm getting it day one so hopefully it's the best one and if it is that's fine with me, but if it's not it won't matter, will still be overhyped by journalists like it is.