Like, holy shit, this is an amazing fight when it comes to the difficulty curve. (I literally just did 4-1 so no spoils pls)
Most of us playing Manic mode from the start of the game will know how boss fights have gone up to this point, you sit back and play safe because the hulking, story-high boss is going to take half of your health bar in one hit. So you beat the hell out of them, then you go back into critical HP or you lose some of your stamina, so you pull back while chugging potions and waiting for your stamina to refill.
Most higher-skill players will probably gravitate towards this, as it's the most consistent strategy - it's also what most other modern hyper-difficult games have taught us such as Dark Souls, where players just rushing in at every moment will get punished HARD and die in a few hits, with the difference that health potions are incredibly limited in a Soulsborne environment. By the time the player reaches Grace City, they're probably pretty familiar with this strategy if they've been playing on harder difficulties, and while the danger still makes the fights tense, they know it by rote and this point alongside waiting for stamina and HP generally not being very fun.
Then, Spring-Legged Samurai comes along, shouts 'FIGHT ME, BITCH 
' at the top of his lungs, before flying halfway across the field and smashing his foot into your face.
I cannot express how much I love this moment, it's basically taking the devs best strategy up to this point of the game, pushing it off a 20-story building and saying 'this is manic, YOU CAN DO BETTER.'
The distance and speed of his basic three hit combo, and the fact that he can change directions entirely on his third hit adds ten times more tension to the fight compared to other times when boss attack patterns were relatively consistent and usually only needed a single dodge to get around if not a dash that didn't consume stamina. It ups the stakes so high compared to the previous stages where players were just starting to get complacent, and just thinking about how they both actively designed for players to do that early on before taking it away and literally pushing into the deep end is just literally amazing.
I FUCKING LOVE IT.
