Characters have changed drastically!

[Ruddy man]

Ryu appears asian now, compared to the original one, his eyes now are most distinctively Asian before more european (bigger eyes).
Black Spider Ninja Clan, in the original appear black faced But in this remake, their faces are white, so much for 'black spider ninja clan' lol!
Rachel also appears semi-darker and has asian eyes compared to the original where her eyes are bigger and more european looking and more fair skin.
Now i can see why Tomonobu Itagaki wasn't involved. Not to mention Ninja gaiden reboot series was mainly aimed for western audience as xbox sold so terribly in japan and was well known most of the sales for the console was for the west.
Now, i haven't compared all the characters, wouldn't doubt the other characters are different from the very few i've seen in the opening of the game.
This is my source; https://youtu.be/z3aRGrmicco