Utterly spectacular. The combat here is unparalleled. I have never been so impressed by swordplay in a video game before. By the end, I felt like a goddamned shinobi myself. It's hard, but it's worth powering through. I saw the PSN trophy stats; 40% of players fall off before beating the first boss. There were plenty of fights I said out loud were "fuckin' impossible". Really knocking my head against the wall. For hours. But, if you surmount the insurmountable, the adrenaline and dopamine that blows through your veins is like nothing else. Plunging my blade into the Sword Saint for the final deathblow made me growl-yell out loud in my empty house after my wife took the kids. Worth every hardship.
The only issue I have with it is just a general fatigue. On NG+, there just isn't any incentive to replay the notoriously difficult, optional bosses that beat your ass for hours previously. Once I did it, I felt like I didn't need to do it again.
Try it and keep trying.