Finished almost everything in NG, just waiting for a couple of Twilight Missions for the platinum. The combat is truly fantastic, and the level design is good as well. Maybe some of the levels were a little bit too similar in appearances but they all had some kind of small gimmick that made them unique. I'm not a fan of the sub missions set in the same areas as the main ones, they feel a bit like padding, but the combat arenas and the sub missions set in new environments were very good as well. I won't touch the subject of loot because it's not very appealing to me but it never detracted from the enjonment of the game either.
My main gripes with the game are enemy variety and the difficulty (or more appropriately, how the game is balanced).
Enemy variety is kind of self explanatory. I think the game needed more enemies or better yet more complex movesets for enemies and bosses. The number itself is fine but you end up fightning a lot of different enemies in the same way because their moves and the way they act are way too similar. Maybe having more mission/regions specific enemies could help as well. They seem to be tailored to a pure action game, and they would be fine there probably, but a character action games is a 10 hours affair mostly, not a 60 hours epic. At some point they start to become just a chore to get through. I enjoyed most of the Yokai Bosses and even most of the gimmick bosses but the human bosses can be obliterated in so many ways that I think they should be rethinked for a sequel or the coming DLCs.
The difficulty was reduced substantially from the Alpha, and it might even be a good thing in some way, but there are just so many ways to "break" the game that, except for a couple of spikes here and there, it becomes a bit too easy. And it's not like there are hidden combination that trivialize the game (there are, but that's not the point), and it's not as simple as saying "just don't use Sloth", because every skill tree have broken ass stuff that can be aquired with ten skill points at most and barely any stat investement. I think they need to rethink skills progression in some way. Gating combos is not the solution, on the contrary I think some abilities like parry should be unlocked from the get go (if balanced accordingly) and the dojo system is a bit too arbitrary. Maybe requiring heavier stat investments for the strongest Omnyo/Ninjutsu and rebalancing the damage of some physical abilities might help, I don't know.
I think Nioh is a fantastic game and as a first attempt is downright impressive, I just hope they focus on the few shortcomings. I'm eager to see what they do in the future.
