Okay I finished the game, jesus christ that ending. I thought I was at the endgame only to have 5 hours left and it moves at a glacial pace. Overall the game is alright but there are massive flaws in it:
Gameplay wise, there is fun in trekking the wide expanses and setting up a delievery route via ziplines. However, there is no real reward that made me want to grind the extra orders once the game stopped giving interesting upgrades as rewards. So I can't think of a lot of replay value (though the game is pretty long as it is). But even then, the gameplay is very stale and the devs can't really do interesting variations on the idea of being a USPS worker.
The action moments are shit, they are universally too long and feel alien to the other 99% of the gameplay time.
Graphically the game looks stunning, but the facial animation, especially for the female actresses looks aweful. It's like the animators tries to exaggerate their expressions, leading to uncanny valley ridiculous faces at dramatic moments. At least most of the female models looks actually bangable (when they don't move their mouths).
The plot is meh, it is overly convoluted and doesn't really explain shit to the player unless he is willing to sit through boring emails. Why the fuck aren't those audio logs? Considering the amount of time the player will just walk from point A to B it would have been a good way to pass the time. The characters themselves also don't talk about anything that isn't plot related, meaning that even after those 30 gameplay hours I don't feel like I know anyone in the game world besides their wikipedia entry.
I think the best example of how the plot is handled badly is an event the player would see in a flashback. Now the event was obviously a good chunk of time ago, but no one remarks on that obvious fact until far later where you are told that. So when the main characters don't seem to care about the plot to remark an obvious error, why should the player care?
The game itself tries to pass the idea of the player going around and creating a massive changes for the various characters, but it doesn't pull the message off. Only once in the entire game you actually interact with the characters and improve your life, other times you just deliever them shit once or twice and ignore their emails like you would ignore that random dude on Facebook that the algorithm decides you really enjoy the latest vacation he went to.
I already said how the game fails politically. Kojima likes the romanticised idea of the USA as a melting pot, but ignores absolutely everything else about the country, and decry the country out of his ivory tower, surrounded by his actor friends for hire.
I usually try to avoid writing how a game should have been, but in this case I would have made the game like an adaption of the anime Kino's Journey. It should be more linear, where each chapter you reach a new hub area with couple of outposts and its own culture and customs, and you actually do multiple quests there for the people and get to know them. You can also use this way add a gameplay twist to make the areas memorable and unique.
Edit: Forgot to mention that the metaphor of "weak strands together become a strong rope" is quite literally the namesake of fascists, who are supposedly represented by the isolasionalists.