NIN is completely fine. It has *been* completely fine, going all the way back to s1. Nearly all of the nerfs are more targeted at them being hilariously broken in Frontlines, with only minor impacts on CC.

NIN is the only class that has to decide between using resources for offense or defense. If they're doing too much damage, you're not pressuring them enough.

Seiton is fine, idiocy of instant death mechanics in a game with low tickrate aside. I've seen many, many different Seiton attempts fail even when I was below 50% because a heal hit just before Seiton took its snapshot. It's really funny watching a NIN stabbing you in Guard when you have 20% HP for no effect.

Seiton needs a complete rework, as does Zantetsuken and boosted Chainsaw, but it's not broken or overpowered.