I'm actually playing through it with a friend in coop these days. About 80 hours in, we're currently in ng+++ to unlock the underworld, which is quite tedious to do, I wish you could unlock all modes without so many ng+ required.
I think the gameplay is cool, I like fists the most out of all the weapons, overall the combats are pretty fun, but outside of this, there are a LOT of problems.
The art direction is incredibly bland, everything feels super generic and repetitive. The level design is boring, the shortcuts are always the same, everytime you start a level you will see the same type of door that's obviously closed and you will open from the other side later. It's either this or a ladder, while souls game have more diverse type of shortcuts that feel more rewarding and clever.
The shortcuts are also actually pretty dumb because they don't carry onto side quests, so playing the side quests just feeling like restarting the levels over and over, there's no sense of progression which is too bad in my opinion, it would have been better if it felt more included into the actual progression of the story.
The sidequests are also very repetitive, especially with the same maps being used over and over. It sometimes doesn't even make any sense, because the maps are re used even in different regions, so sometimes you're in a completely different region, but the level will be one from region 1 lol. Real immersion killer and super repetitive. There are even maps re used from Nioh 1. It just really feels lazy.
The loot system is horrible for me. There is way too much lot, you're constantly looting new objects and end up with an inventory full of hundreds of new items, which totally kill my motivation to make a clean build, because the game wants you to renew it every 30 minutes. It's really too much a feels like a chore to keep up with. I usually end up selling all of it without even looking at it because I know it's useless, that I will get something better the next mission anyway, so I only check every few hours.
One other really annoying thing in the game are the ranged ennemies. EVERY combats in the game, you will have several ennemies in the distance, on a rooftop or something, shooting at you. It ends up being extremely annoying, not really for a matter of difficulty, but just because it kills the pace of the game. Every encounter you have to draw your ranged weapon and check for all ennemies and get rid of them to finally be able to fight the main ennemies, it's incredibly repetitive and annoying, it really ruins a lot of the combats in my opinion. There are also a lot of... "difficulty" methods that feel lazy, like ennemies always waiting for you hidden in a corner, or the same repetitive traps etc.
The technical aspect is also really bad, with crazy pop in all the time, you even have huge element of background that appear and disappear suddenly, like even whole mountains, it's ridiculous.
Despite all of this, I still played it for a long time because the core mecanics are fun, especially in coop, but I definitely wouldn't have played this much alone, it's just way too repetitive. It's too bad because I really think there is the potential for an actual great game, but the whole structure and content feels extremely lazy, it could be a lot better.
Sorry for the long post