I've done everything I want to do in Sekiro which is mostly everything. NG+7 is apparently the final New Game Plus cycle with a difficulty increase, so I wanted to see if I could do it. In addition to this, I also beat the three "secret" gauntlet bosses.
What a game. The sense of satisfaction when you completely nail a boss fight is so powerful. By NG+7, anything less than a perfect deflect fills up an enormous amount of your posture bar, so you have to be on your A game. With a full posture bar, your posture doesn't break as long as you make perfect deflects, so you're constantly balancing on a knife's edge (for the most part, anyway--when your posture is broken, you can usually just roll out of the way to safety). In my NG+7 run, the only time I had a true death was during Headless Ape's second phase; I one-try'd every other boss.
Storywise I really like that Sekiro is a much more personal game for its characters. In Dark Souls, all of the important events and people are so far away that I didn't really feel like I connected with them. They were cool to learn about, certainly, but I think the only real "oh shit" moment I had in Dark Souls 1 was the Lautrec "Well, look at you" moment. But Sekiro got me invested in Wolf, Kuro, even Isshin. I wanted to see these characters succeed, even as war burbled around them and even as their outcomes looked bleak. The fascinating Buddhist mythos of the world drove each character's every move and motivation in a way that felt active and involved, and the characters evolved in ways that were surprising, and each one held really fun connections in their own histories. I think this is FromSoft's best story in their modern age.