Played Dark souls or Blood Borne before this? dont expect ANY of it to carry over.

In Sekiro, you are a ninja. Play like a ninja and you'll have an easier time than just rushing like a warrior.

And regarding perilous attacks, dont look for the symbol, hear for the sound and look for the stance of the enemy.

If you dont know where to go, look up. there might be something you can grapple to, to continue.

Bosses, if you cant pass them after who knows how many tries, sleep on it (IRL). it helps.

Also, some of them have what i call 'damage windows' these are windows in the boss' moveset that allows you to get a hit in or two.

My opinion; If you took my first impression (which was at release), i would've disliked it because i took none of the tips above into consideration. tried again after i dont know how long, began to play like you should and had a much easier time. though last boss, uhm... difficult is an understatement.