I'm surprised someone would say this.
It has extremely fast paced and smooth action combat, thus giving the player a large amount of freedom and mobility. Her little robot that shoots bullets also has some level of usability, as it actually does some level of damage, whereas most games that have something similar make that do next to nothing in damage, including the original Nier. The game also made clever use of transitions between different genres, and it did so so smoothly that it felt natural. At no point did the transitions to being styled more like a platformer or more like a shmup ever come off as jarring or as their own thing; even in the original game, some of these elements seemed more out of place, where the visual novel sections were their own thing and the mansion "horror" section took large amounts of control away from the player without changing camera perspective very much, thus making it seem as if the game is just limiting you rather than smoothly creating that transition between genres. I don't think most games can successfully pull off these sorts of genre changes.
You mentioned Dark Souls and Bloodborne in your post, but I think those games actually suffer in terms of gameplay due to the amount they limit the player's mobility, having generally extremely slow movement (and thus taking control away from the player). I also think the games are a bit unfair; they do not give much guidance to the player on where to go, and the game also puts a lot of traps you generally can't see coming in your way, thus making the game a large bit of trial and error.
Not that I'm saying such games are bad, but just that I'm surprised you would consider Nier Automata's demo howing of it being a poor game when it improves upon the more negative aspects of other games you mentioned in your post. Nier Automata is a very fair game, in some ways reminiscent of Metal Gear Rising, but without being as easy as MGR.
