I played it until shortly after getting to the second map area back when it came out, but lost like 10+ hours of progress because of some cloud save fuckery, recently started playing again from the start.
Fuck it’s fun man. I’ve heard it ends disappointingly and is considered “unfinished” (no spoilers please!), but fuck, it’s so fun just running around tranquilising dudes and fultoning tanks. I’ve been progressing the story really slowly because I’ve just been free-roaming with a podcast on, going from outpost to outpost just emptying the place out. I’ve also gotten side tracked going back to get S-ranks on old missions. Even that sting of the MGS theme you get at the mission report screen when you get an S-rank, so great. A lot of nice touches like that.
The controls are so responsive and smooth, it’s really the height of what that series set out to be. And the amount of stupid stuff you can do with weapons and items, and the classic MGS weirdness sprinkled on top, so damn good.
It’s also one of those games that gives you a really satisfying feeling of progression, starting out with lame weapons and slowly developing more powerful and useful stuff, expanding Mother Base and getting bonuses from the various “platforms”, and even just you becoming better as you explore the mechanics and learn the layouts of the maps.
Very, very good game.
If you're on PC use SnakeBite to install Infinite Heaven once you've finished the main game. Easily added another hundred hours to my playtime.
My personal mod list that adds flavour and content without breaking the game:
You can grab all these from NexusMods.