I believe that Rupert Goold's adaptation portrays Lady Macbeth precisely how Shakespeare intended. At the beginning of the play she is truly evil. Her actions are not merely to impress her husband and encourage him to kill Duncan. This is aptly illustrated by her soliloquy when she receives Macbeth's letter informing her about the witches' predictions and that one prediction had been realized. Lady Macbeth says:
... yet do I fear thy nature:
it is too full o' the milk of human kindness
To catch the nearest way
These words suggest that she herself has no remorse and will do whatever is needed to usurp Duncan's throne. She fears that Macbeth is not ruthless enough. She, however, at this point, has no such softness, which is an inherent evil. She wishes for Macbeth to rush home so that she may:
... pour my spirits in thine ear;
And chastise with the valour of mine tongue
All that impedes thee from the golden round,
In these words, we see the depth of Lady Macbeth's evil. She will encourage her husband to overcome all that stands in his way of obtaining the crown. She later calls on the powers of darkness to "unsex" her and
fill me from the crown to the toe top-full
Of direst cruelty! make thick my blood;
Stop up the access and passage to remorse,
That no compunctious visitings of nature
Shake my fell purpose ...
This is a deliberate wish by her to be completely overwhelmed by evil to such an extent that her feminine qualities be removed, that she should be bereft of any remorse and that not even that which is natural should withhold her. Rupert Goold's adaptation accurately reflects this lust.
When Lady Macbeth later meets her husband and he expresses doubt about continuing with Duncan's murder, she calls him a coward that has relented on a pledge and says that she would even dash out the brains of a suckling babe if she had vowed to do so. She is the one who plots Duncan's murder. She plies his guards with alcohol and later returns the murder weapons to his chamber when her husband fails to do so. This is not just an act and this fact is expertly portrayed in the movie.
It is only towards the end of the play that Lady Macbeth shows guilt and regret, not because she is saddened by what they have done, but because their deed has not brought them the happiness and success they sought. She is also shocked and overwhelmed by how brutal and ruthless her husband has become. She sleepwalks and is overwhelmed by despair, only now realizing the true nature of the crime that they committed. However, she does not seek forgiveness or grace from God. At no point in the play or the movie do we see Lady Macbeth repentant. Her only outcome is death.