Took around 45 hours to beat on the first playthrough with very heavy exploration and 2 instances of farming(Edit:- Forgot to mention, I got the Return ending which is takes the longest to achieve it seems. And apparently there are 3 other endings to this game, so great replay value).

This game is difficult if you are used to playing Dark Souls-ish games as it makes you unlearn a lot of the mechanics from those games. Instead of block/rolling/continuous evasion, this game forces you to go head-on and clash the glorious nippon steel with your foes at full throttle.
If you keep your block up, prepare to get punished after getting posture broken. The trick is to learn the enemies attack patterns and deflect his attacks by just blocking the instant his/her damage is about to hit you. All the other while, you need to be aggressive and target their posture meter down to get deathblows. If you consider enemies having just 2 resource bars (health and posture in sekiro instead of health and stamina from souls games), then focusing on posture breaks is what works in Sekiro. At the end of the day Sekiro's combat seems close to a rhythm game.

That said, there is a lot of flexibility in Sekiro in terms of how you want to approach fights. The boss encounters are memorable and the mini-bosses are basically skill-checks to see if you have really learnt the mechanics of the game up till that encounter.

And there are multiple endings, and certain bosses are locked out if you chase certain endings.So there is quite a bit of replay value here. Not to mention NG+, demon's bell and no Kuro's Charm challenges if you really want to spice up the difficulty. While it is a complete game on its own, I do wish they launch some DLCs. There are certain stories and characters mentioned in the lore of this game which would make fantastic DLC additions.