Extremely challenging and has a steep learning curve. I've played the Dark Souls series and Bloodborne is my favorite game of all time. If you come in to this game thinking you can breeze through it because you've beaten the others, you are sorely mistaken. You need to forget how you played in the past games, because roll dodge is not a viable tactic in this game. Parrying and stealth is very much at the center of this game. Sekiro forces you to play aggressive a lot, otherwise hit and run is a tactic for which I've used on parts with too many enemies to confront at once.
A lot of bosses in a row and a somewhat linear experience is a little bit of a let down for me. Not as much of a free roam world as I had hoped for but the storyline and combat system make up for it without a doubt. No customization other than your shinobi prosthetic arm swappable skills was meant so you center more on the combat system of the game. You earn skill points from combat to upgrade passive and usable skills. There are a good amount of quick items as well that you're able to use during combat.
Overall, I am happy with my purchase and enjoy the the butt kicking I have been taking. Learning something new from each mistake and death is the very core of this game. Perfecting your timing and other skills will take time. With enough patience, anyone can beat this game.