Well... I played 4h non stop already on hard difficulty.....I don't want to say nothing spoilery, but if the "game concept" was the thing that makes the game love or hate the game, i'm now allowed to say that....
I love it.
Completely original, full thought, continuously taking decisions, in a super beautiful and realistic landscape. And yes, things are calm most of the time..., but oh my god when things suddenly become ...."tense". You can feel it. And it makes absolute sense that feeling of relief reaching a base to rest up..., physically and mentally. I'm completely inmersed in this game. And this is just the beginning of the game. I still need to see the rest of the mechanics and concpets of this game.
As for the rest of the game. Is a Kojima game in the best way possible. Impecable presentation, full of cinematic cutscenes with surprisingly everything making sense. This is the best work in this deparment Kojima has made until now.
This game can not be compared to anything else. It requires long periods of gameplay to enjoy it, because it's a slow game. Yes..., is a walking/hiking simulator but is a damn good one, full of interesting things happening around you. I'll have to see if the gaming loop is still interesting after 30-40h, but right now, it is.
If you are looking for a unique game and you're tired of the same generic gaming mechanics for RPGs, shooters, action games and want an ambicious story driven game with top tier production values this is your game. There is nothing else like this in in the market.