Edit: @hiroy in my opinion it does not have the same sophistication of level design that I would call it a metroidvania.
It's just more open than games that deliver a similar experience. But I don't feel like that the added space is used for gameplay in very meaningful ways nor that explorating it adds any sense achievement. Also the fact that you can earn a skill that highlights almost everything that's collectable rather transforms any exploration into a fetch mission.The tombs are very akin to assassins creed tombs with a few very minor bits that only open up after you get a certain item.
In theory, I do like the idea behind the AC's tomb stages, as much as I hate the rewards in them. They always struck me as experimental puzzle platformers that I'd really like to see in its own game. Sort of like an evolved take on the Zelda formula, only with boss battles that could be defeated in a variety of ways depending on how strong you are due to exploration(rather than strictly using area related items in a predictable fashion).
I guess I'll give it buy when it's cheaper.