1 She is forceful and masterful; she takes full control: "Leave all the rest to me."  She is a shrewd judge of her husband's character and knows how to manipulate him.  She is also totally ruthless: "And fill me, from the crown to the toe, top full / of direst cruelty."  This side of her character is also evident in the murder scene.

2 She is deceitful and tells Macbeth to be deceitful too: "look like / th'innocent flower, But be the serpent under't."  She also manages to convincingly faint at the news of Duncan's murder (having pretended to be glad to see him when he first arrived at the castle.)

3 She puts on a brave face "Things without all remedy / Should be without regard: what's done is done."  She is being supportive to Macbeth and playing the part of the good wife.

4 She is also human: she couldn't kill Duncan herself because he looked like her father - so she does have some scruples, although she doesn't let them interfere too much  with her plans.

5 This is because she is ambitious - which is why she pushes Macbeth into murdering Duncan.  She revels in his address to her in the letter, where she is referred to as "my dearest partner of greatness."

6 In the end she is a pathetic character; she is, despite her apparent viciousness, a human being, her mind unhinged by the guilt she feels of the murder that she re-lives constantly in her sleep walking.  Everything has backfired on her.  The murder is not so easily forgotten.  "A little water clears us of this deed"  ironically changes to "All the perfumes of Arabia will not sweeten this little hand."

7 She can be seen as another Eve (of Adam and Eve fame)  She tempts Macbeth as Eve did Adam.