What does Act I, Scene 7, of Macbeth suggest about Lady Macbeth?

In this scene, we learn Lady Macbeth is ruthless, ambitious, and controls Macbeth. 

Macbeth was initially excited about the prospect of being king, and was ready to kill Duncan to take the throne. When Macbeth returns home, however, he begins to change his mind. Macbeth is dithering about it, trying to decide if he should kill the king. Lady Macbeth is not happy about this. She scolds Macbeth for being cowardly and indecisive. 

Art thou afeard
To be the same in thine own act and valour
As thou art in desire? Wouldst thou have that
Which thou esteem'st the ornament of life,
And live a coward in thine own esteem,
Letting 'I dare not' wait upon 'I would,'
Like the poor cat i' the adage (Act I, Scene 7)? 

From this, we learn Lady Macbeth is ambitious. She may even be more ambitious than her husband, as he is willing to let the whole thing go. Lady Macbeth will not. She wants Macbeth to act and will not make it easy for him to back down. 

Lady Macbeth is ruthless. When Macbeth asks what should happen if they fail, Lady Macbeth tells him they cannot fail if he is strong and brave enough. If they fail, it is because Macbeth is a coward. He should do his part, and she will do hers. 

We fail!
But screw your courage to the sticking-place,
And we'll not fail. When Duncan is asleep—
Whereto the rather shall his day's hard journey
Soundly invite him—his two chamberlains
Will I with wine and wassail so convince
That memory, the warder of the brain,
Shall be a fume, and the receipt of reason
A limbeck only (Act 1, Scene 7).

Lady Macbeth will make sure Duncan’s guards are drugged so they are easy to kill. As long as Macbeth takes kills who he is supposed to kill, everything will go swimmingly. Lady Macbeth even later says she could have stabbed Duncan herself, but he looked like her father and she couldn't make herself do it.

Lady Macbeth clearly has a lot of influence on her husband. He was willing to drop the murder plot and remain Thane of Cawdor, but he made Lady Macbeth have bloodlust by telling her the witches said he would be king. Lady Macbeth wants to make sure her husband becomes king, and he goes along with her plans.