Sekiro defeated via "Return" ending. 73 hours. I completed everything except the mutually-exclusive bosses. It's a solid, standalone experience. I loved the combat and the tightly-knit kit of shinobi tools and skills and arts, but I would've enjoyed a way to hot-swap between combat arts (yes yes, technically you can pause and equip another one at any time). I wish more Ninjutsu abilities had been added (felt kinda like an afterthought).
I can't take a step back and compare to other Soulsborne games quite yet but I'm definitely fond of it. It was much harder in some respects but easier in others. I think it was designed brilliantly and purposefully in order to punish Souls and Bloodborne players who'd grown comfortable with a certain paradigm.
I also booted up Bloodborne (two friends are going through it for the first time) and could appreciate the differences in combat and enemy placement: enemies are far easier 1-on-1 in Bloodborne, but the game throws far more mobs of enemies at you than in Sekiro, which gives you more chances to flee and more chances to attack from an unexpected angle.
Will replay many more times.
EDIT: oh and I love the deflect mechanic. Technically your deflect will never, ever break as long as you keep deflecting consecutive attacks. I think as time goes on the fanbase will grow to appreciate how nuanced and well-designed the combat is. The posture vs vitality mechanic works very well and gives the player a lot of rock-paper-scissors choices in battle. Focus on stomping his head after that sweep, or focus on deflecting a certain combo, or using firecrackers during a certain attack. There are a lot of this-beats-that exploits in the game. I feel like it was the least "git gud" Soulsborne and the most "git observant". Enemy behavior was harder to bait successfully.
EDIT 2: dang, enemies in NG+ are far more aggressive. I love it. Most FROM games just amp up the damage and the health/resistance in each consecutive NG+, but in Sekiro it feels as though their combat AI has gotten a tweak as well.
Terranigma is great but it's definitely a slow burn.
Seconded. The first half of the game is essentially linear. Don't get the impression that you have freedom to explore a lot of different subquests until you've made quite a lot of progress.