The game is learning.

There's some reaction element, but the core loop is learning how to be optimally positioned to use your weapon, how to optimally pace your attacks, when your attacks leave you vulnerable. Then once you get that, you do the same with enemies. You learn where they hit hardest, what you can avoid, what their tells are, and when they're vulnerable.

If you're willing to learn and approach the game with learning as a goal, and understanding that you'll die as part of that learning process, they're great, because they do a really good job of creating difficulty in a way that almost all damage is predictable and avoidable if you know what you're looking at and approach it the right way.

If you just want to button mash you're going to have a bad time.