I'm only on Genichiro, so I can't fully say yet, but in one way I think it's better. While I wouldn't necessarily say the gameplay is better, I do like that it feels as if it requires more skill than the Souls games. Considering the Soulsborne games were RPG's, you could more or less level your way past things if you wanted to while in Sekiro you can't really do that. The thing I'm not liking quite as much is the environments, but again, I'm not that far in and I do like the environments mind you. I haven't seen anyone compare it to Nioh though, which I think is also an interesting comparison only because both deal with Japanese Samurai/ninja stuff.
How do these things compare:
- Challenge (which I am separating from gameplay even though they can go hand-in-hand)
- Enemy types
I'm not sure about gameplay overall; both are good. Sekiro has a little more since you can now sneak and grapple. I think challenge perhaps balances out to be the same. While I think it takes more skill to do Sekiro, it might arguably be easier if you master it because enemies/bosses don't last too long if you have all the right moves down. In the Soulsborne games, many times bosses just take a lot of hits and it's about waiting to strike. So far, I like the Soulsborne environments more, although I like Sekiro's environments a bit more than what was in Nioh. I liked Nioh's environments, but I didn't like that it retreaded them again and again with a new layer of paint for the side missions.
Enemy type and bosses are about the same in this too. I would say that in the Souls games, enemies and even bosses up to this point felt a bit (from an artistic design, sound perspective) more imposing which I loved. I like that the soundtrack plays a bit more in Sekiro, and I like it more than what was in DS3 (DS3's soundtrack was too operatic for my tastes), but aside from that, I like the soundtrack in the other Soulsborne games and Nioh more. I still have a lot more to go in Sekiro, and even though I sometimes think I may not get through it, I just know I will and I am having a blast (despite getting frustrated at times).