Yes, some sequels recycle content but the extent can differ a lot. I don't get this argument at all. It might be that Nioh 2 recycles a ton of assets from the first game in which case it would be a valid complaint. Based on my expercience with Nioh this wouldn't surprise me as that game already recycled a ton of content.If there was only new enemies and areas in the game, people would also complain there's not enough variety.
There's reused elements in every sequel out there, including Dark Souls. That review honestly sounds like he replayed the first game just before 2, which would obviously bring a lot of fatigue with it.
edit:
That'd make no sense. You know that Nioh is based on historical characters, right?
We'll see soon enough.