A big problem has been heavy criticism of the decision to cast Scarlett Johansson as the main character. The argument is that they should have gotten a Japanese actress to play the role, since the character is Japanese.
[Warning–I’m about to spoil a few plot points, so proceed with caution.]
But the thing is, the whole premise of the movie is that a sinister robotics corporation took the brain of a woman named Motoko Kusanagi and placed it inside an artificial body. (And re-named her “Mira Killian”.) We only see Kusanagi’s human body in a brief flashback, and her features are difficult to discern in the scene. Johansson just plays the artificial machine body in which Kusanagi’s brain is housed.
And this serves a dramatic purpose in the film: in the scene where Kusanagi in her mechanical body is reunited with her mother, the fact that they no longer have any resemblance makes the scene very poignant. Even though she has her memories back, it underscores that something has been permanently taken away from them by the operation.
In addition, Johansson’s performance throughout the film was fine. So the whole controversy is really misguided–I suspect a lot of the people talking about it didn’t see the movie or even know the plot.