This game is perfectly competent. That's about the best compliment I can give it. It does a lot of things that have been done before, competently. It does some new and interesting things but they don't blow you away, they're competent. In other words, it's a pretty bog-standard open world adventure game with a check-list, "towers", and missions where you follow people slowly without getting too close.
Starting with the most obvious elements of the game, the combat and stealth, there are a few things that work well in its favour. The combat skills make for fun, high octane, fight scenes that are super photogenic and can, at times, feel super cool. Moves like the heavenly strike make combos flashy and dynamic, knowing the best ways to launch your combos and the best finishers to use is very satisfying.
That said, the combat isn't without its flaws. With no lock on system in place, large fights can get sloppy and can result in moments where you feel robbed of success. Generally, when fighting, you use the left stick to direct your attacks towards a target but at times Jin will attack the wrong enemy or a closer target than where you're directing him. More than once I broke down a foe's guard and hit the buttons for a heavenly strike only to have Jin launch the attack off to the right, at a guy who took almost no damage since I hadn't hit him at all yet.
Moving on, the stealth is rudimentary. If you've played Assassin's Creed you know exactly what this stealth is like. It doesn't really add anything to the formula, avoid lines of sight and stab guys. You can level up to do chain assassinations and get gear that makes you harder to detect but that's about it. Nothing to write home about.
Stealth missions, because of this design, can be confusing and frustrating at times. Missions where getting caught is a fail state can feel incredibly linear, with a single path to progress through, which seems pointless in my view. What's the point of all these skills if all I need to do is crouch walk along the path you've pre-designed to get me through? On one occasion I failed to sneak but must have hit a check point because I loaded forward in the mission, I still have no idea how to succeed at that particular mission.
The story is alright, maybe one of the weaker points. None of the characters really have personality, and Jin's journey to becoming the Ghost is weakened by this. The game suffers from a real "events as plot" mindset, there aren't many occasions where you really spend time with your allies to get to know who they are as people. You only show up to help them murder the people that they're mad at so that, when it's time, they'll show up to help you murder the people that you're mad at.
Spoiler territory now: The side characters are fine. Whatever. A lady samurai on a murderous revenge rampage is fine. It would have been nice to know who she was as a person better but oh well. The characters that really come across as weak are Jin, Yuna, Ryuzo, Taka, and good ol' Uncle Shimura. Playing as Jin you don't really spend any time with his uncle or his childhood friend. There are a few flashbacks to Jin's past where his uncle is fatherly but aside from a combat tutorial they're non-interactive. Ryuzo does not appear in flashbacks. This kind of drains the impact of his betrayal, as well as the conflict between Shimura's honour and Jin's fall from grace.
Yuna and Taka are better served, but ultimately Taka dies off so fast his sacrifice is more of a gotcha than something the writing built up to. Yuna gets more time with Jin and we learn of her past, her abusive mother, and why she and Taka ran away but nothing else. Additionally, we have no idea about her values or beliefs, she's just there for the ride, I guess.
The plot is flat. It's serviceable if you turn your brain off, but it's not worth much consideration.
Where this game really shines is the exploration. When you go off the story and quest rails to play with the toolbox that the devs have given you. Raiding camps, dueling, assassinating, and mowing down enemies is what the game was built for. The above gripes can make for frustrating moments, but they don't happen in every encounter, and if you're the kind of person who likes completing a collectathon in an open world then this game scratches that itch.
The world is beautiful, the minimalistic HUD and the photo mode really add to this. Without the constraints of the plot the game is much, much better.
Ghost of Tsushima is a totally passable experience. The plot's not great but it is short at least, and the combat can be fun when it opts to function correctly. The world is beautiful, the sound is excellent, and if you need a little vacation into an action game with colour and interesting vistas to explore, you could do worse than this.