I'm not very far at the moment (I think I'm about to fight the first real boss?). I'm not fully sold on it yet, but it also hasn't "clicked" with me yet so it's hard to say.
I notably really like the level design. Grappling is super fun and the levels are definitely built to use all the skills you have access to in order to gain a leg up on your enemy, shinobi style. The stealth aspect is definitely weak, but it does function, at least.
Not really sold on the combat and enemy encounter design so far though. The combat trends towards being hyper aggressive and does a decent attempt at melding offense with defense, but I feel like it doesn't fully get it right. Deflecting feels a bit wonky and switching from offense to defense isn't as fluid as it is in Platinum's offerings, but I think that's due to a) me not fully understanding how the inputs work, and b) how animation cancelling works in Sekiro. I'm also not a huge fan of the thrust/sweep/grab system because the death kanji isn't a particularly good tell; your eyes are immediately drawn to the big red kanji character when you're actually supposed to pay attention to the animation (which can also be obscured by said kanji), so it's really hard to get a good grasp on what the attack is going to be before you get hit by it. If you're against an enemy with multiple attack types, countering them feels like a guessing game instead of something in your control. If From wanted to properly signpost those attacks, they'd either color-code the kanji character to each type of attack, or remove the kanji entirely and replace it with something that doesn't take away/distract from the enemy's animation (e.g. an aura and/or very distinct sound effects). The latter would probably be preferred.
In regards to encounter design, the game really emphasizes stealth 'n' run/hide over direct confrontation because of how many enemies you have to deal with vs. how easily you die in regular combat, which wouldn't be a bad idea if more thought was put into the stealth, and if enemies reacted differently to the world around them (mainly they don't bat an eye when they see a dead body lying on the ground, but sometimes can be totally clairvoyant regardless of your attempts to be stealthy). This is especially true of mini-boss encounters, where they have a boatload of posture yet can two-shot you no problem because you have the health bar of a twig with very few uses of the healing gourd, so you always want to stealth away a health bar so that you deal with the frustration of actually fighting it for less time. I haven't really felt satisfied beating any of the mini-bosses yet since it felt like I wasn't beating them with skill, but by getting some lucky deflects. One of the encounters I just did was notably really tedious since I had to stealth through a ton of enemies just to fight the mini-boss 1-on-1, but I kept dying to the mini-boss so I had to constantly stealth through the same throng of enemies over and over, which was just a massive waste of time.
Also, Dragonrot is a 100% garbage mechanic and I will not be convinced otherwise. The game already punishes the player really hard for dying via permanent losses of SP/money (unlike in the Souls games where you could retrieve lost Souls unless you died before retrieving them), so Dragonrot is just FromSoft's way of kicking the player while they're down. It should never have been put into the game.
I do want to keep going to see if the combat ends up clicking after a while like blocking in Metal Gear Rising did, but we'll see.