First off, I'm not a Kojima fanatic, I like his games, and he seems like a good guy, but I've only ever completed one Metal Gear solid game. Secondly, I've only played about five hours (on third chapter) or so total, and from what I've read, that's just scratching the surface (Total playtime is approx. 45hrs, 100% completion about 60hrs). Third, I'm going to try and keep this as spoiler-free as possible and just stick with generalities if possible. And lastly, this is my first time writing a review, so my apologies if it's a bit rough.
Summary: It's a walking and delivery simulator game with a story. However, this is a Hideo Kojima walking/delivery simulator, which means it's much more than that.
Basic Premise: Without giving away too much of the story, basically, cities/communities/towns/installations have been pretty much cut off from each other. And due to specific environmental, terrain, and other hazards, air travel is not possible, and trucking or even motorbike travel isn't always reliable or available. Hence, deliveries of supplies/drugs/parts/etc.. all need to handled by porters like your character. However, just like real life, carrying several cases with an average total weight of 125lb+, bush-whacking over rough terrain filled with additional hazards isn't that easy.
The good/great: Story is weird, but so far, it's very well done, but it's Hideo Kojima's story, and they tend to lean towards weird but semi-believable. The graphics are outstanding, the environmental effects are lovely, and it has a really good sense of atmosphere. Sound quality is excellent, and at some points along your travels, full songs from the various bands will kick in, and they fit very well with what you are doing. Not EDM, not rock, not pop, I would say it fits in the chill genre (song from the game: Don't Be So Serious by Low Roar ). Gear and cargo has weight and inertia, and those have meaning in the game. There is a simple crafting mechanic and you can carry crafted gear to make your life easier, but it comes at a cost of weight. Sure you could carry 12 ladders, but it's going to be very hard going with all that weight plus your cargo. Re-spawning happens where you bit the dust, so you don't have to start the entire journey over again. Compared to other "walking sim" games like DayZ or The Long Walk, you are not going to directly die from starvation, dehydration, hypo/ hyperthermia , and lack of sleep. You are also not going to break bones, or twist ankles from falling(short heights), stumbling, or sliding. Controls are easy to use and are pretty intuitive.
The bad/weird: Personally, I haven't found anything horribly wrong in it so far. However, you will need to suspend your belief a bit here and there. For one thing, how far you travel doesn't match up with how far you go on the world map. There is some blatant product placement, but I think it fits in the world. There are many cut scenes, and lots of reading if you want to get more immersed in the world. And there's an assumption that a good rain suit will keep you from getting wet at all. Basically, all the stuff that makes a video game a video game and not a holodeck simulation of the real world. The interface could use some work, it can be difficult to remember what needs a long press vs a short tap on a button.
Multiplayer: It's a different kind of multiplayer. You can interact with your world by building structures, putting up signs, placing climbing/traversing ladders/ropes. But these will appear in other players' game world, and vice versa. Example: You might be trying to figure out if it's better to go around or climb over the ridge and go over the top to get to your destination. Meanwhile, in my game, I decided to go over the top of the ridge. To do that, I had to place a climbing ladder, and I used a rope to lower myself down on the other side. In your game, you would see that player "Kahoko" has placed a ladder and rope and the path they took. And when you get to that spot, the ladder/rope would be there available for your use, and you can even leave a "like" for that player if you thought it was useful. Another example on a trip to a power station. When I crested the ridge, I found some signs that other players had left warning me of trouble up ahead, and again I can leave a "like" if that was useful. You can also donate gear to a shared box so other players can use those items. As far as I know, other players cannot enter your game. And I'm not sure how it decides what to show from who. It's not showing everything from every player, otherwise my map would be covered in bridges/ladders/ropes/etc. I think I'm seeing things from about 6-8 different people.
My take: All in all, I find it enjoyable and fun to play, and while it is a walking sim, honestly, it could have been a lot worse. Your main difficulties are balancing your load, traversing Icelandic levels of terrain, and dealing with game-play elements central to the story. You can bleed to death, and one of the ways that can happen is if your footwear loses all of its durability. But carrying an extra pair of boots isn't a big deal. There are some timed deliveries, but most of the deliveries are not timed. What is a factor is the condition of the deliverables. As I said earlier, you may have a choice between going over a ridge-line, which would be faster and more direct, or taking a longer way around. The faster way will have a much higher chance of falling and damaging your gear and the shipment. Whereas the longer route will be safer but will take more time. Also general exposure to the unique weather/environmental elements of the game world will have their on effects on the condition of the equipment. Limiting your exposure to these elements might mean taking risks is a better idea, but if you are carrying a ton of stuff, the longer route would be a better choice since one bad fall could do a ton more damage than taking the long way around and having a longer exposure to the elements.
Should I play it?: Well, it depends. If you are looking for a Fallout, RDR2, GTA type game with lots of explosions, gun battles, driving around, etc. then this is not the game for you. If you are looking for a Metal Gear type game, then it's not for you either. This game embodies the Emerson quote, "It's not the destination; it's the journey." If you want a game with a good story, a great atmosphere, where you can plan your own route, plan the gear you might need, and enjoy moments of solitude and hiking, with some combat/sneaking around then it might be the game for you.