In a recent interview with IGN, Team Ninja studio head Yosuke Hayashi discussed how Ninja Gaiden III's difficulty will compare to its demanding predecessors. “We are trying to design the game so that anyone can take on the game and experience the action. You can expect it to be less demanding than Ninja Gaiden II, it won't be as hard as that.” He continues, “It might taste a bit different, but it will still stay Ninja Gaiden, and we don't think the difficulty is a big issue.”
While it sounds like the default difficulty setting might be a little more forgiving, we'd be surprised if there weren't traditionally difficult settings available for more experienced players. After all, what's a Ninja Gaiden game without dying a few dozen times?