In the play, Macbeth, what does lady Macbeth think of her husband?

Lady Macbeth thinks differently of her husband at different times in the play, depending on the situation. In Act 1, scene 5, after she has received his letter, she expresses pride at his achieving the title Thane of Cawdor. However, she feels that her husband is too gentle and kind to drive his ambition further, for the witches had also told him that he would be 'king hereafter.' Lady Macbeth thinks that her husband does not have the ruthlessness required in achieving such a lofty goal, for, surely, he can only become king if he should do so by foul means. She states:

...yet do I fear thy nature;
It is too full o' the milk of human kindness
To catch the nearest way: thou wouldst be great;
Art not without ambition, but without
The illness should attend it: what thou wouldst highly,
That wouldst thou holily; wouldst not play false,
And yet wouldst wrongly win:

She knows that Macbeth is ambitious, but she also recognizes that he does not have the malevolence required to achieve what he wants. She wishes that he should rush home so that she can fill his head with evil thoughts and drive away all ideas that might withhold him from committing the foul acts that he would need to perform in order to achieve the crown.

Later, when Macbeth arrives at the castle, she thinks that he is too open-faced and expressive and that others might read in his face 'strange matters.' She asks him to adopt a different look and present an image of goodness and conviviality, whilst he is actually a viper ready to strike:

...look like the innocent flower,
But be the serpent under't.

Once they have plotted to kill king Duncan, Macbeth tells her, 'We shall proceed no further in this business.' He has given considerable thought to their plan and wants to end it. Lady Macbeth is angry and thinks that he is a coward. She accuses him of having expressed a hope as if he were drunk. She is obviously disappointed at his sudden cowardice and says that she would from this time measure his love on that basis. She compares him to a cat that wants to eat fish but is afraid to get its feet wet.

She, furthermore, thinks of him as one who cannot keep a promise for she asks him what has now made him break the vow that he had made to her. As an example of what she requires of him, she mentions that she would rip a suckling baby from her breast and dash its brains out if that had been what she promised to do. She uses this disgusting image to urge her husband into reconsidering his decision.

Lady Macbeth thinks her husband is afraid when he considers the possibility of their failure in this plot. She tells him:

...screw your courage to the sticking-place,
And we'll not fail.

In other words, he needs to regain his courage and they would be successful. She then carefully outlines her plan to ensure the success of their abhorrent mischief.

There are a number of instances where Lady Macbeth questions her husband's character and courage. When he, for instance, returns from Duncan's chamber after having murdered him, Macbeth expresses the fact that his hands are 'a sorry sight.' She believes him foolish to think so and reprimands him. She thinks him weak-minded to spend so much thought on the fact that he could not say 'amen' after the murder and that he had heard voices. She calls him 'brainsickly' for thinking in such terms.

When Macbeth refuses to return to Duncan's chamber to replace the guards' knives, his wife loses patience with him and calls him 'infirm of purpose' once again reflecting on his courage. She later returns with her hands all bloody and emphasizes the fact that she thinks he is a coward by saying:

My hands are of your colour; but I shame
To wear a heart so white.

This belief that her husband is a coward is again confirmed later when Macbeth imagines seeing Banquo's ghost after he had him murdered. When he tells her that it is a terrible vision that he sees, she remarks:

O proper stuff!
This is the very painting of your fear:
This is the air-drawn dagger which, you said,
Led you to Duncan. O, these flaws and starts,
Impostors to true fear, would well become
A woman's story at a winter's fire,
Authorized by her grandam. Shame itself!
Why do you make such faces? When all's done,
You look but on a stool.

She is ashamed of him and how he behaves. She calls him 'unmanned in folly' - his foolishness makes a coward of him.

It is probably Lady Macbeth's resolute determination and her ruthless criticism of her husband as well as her urging him to commit the vile deeds that he did, which eventually turn Macbeth into the malevolent and ruthless tyrant he becomes. In the end, the depth of his evil becomes too much for her and she cannot contain her guilt. She loses her mind and eventually commits suicide.