1 For all but the very last part of his life, Macbeth was a good and noble soldier, serving his king well; we first see him fighting valiantly in an uneven struggle against the Norweyans for Duncan.

2 There is something suspicious about Macbeth from the beginning.  There is a the link between him and the witches, hinted at by their both using "Fair is foul" and "So foul and fair a day".  As soon as he is addressed by the witches, he's speechless and he later hints as to why in: "Why do I yield to that suggestion / Whose horrid image doth unfix my hair..."  We can guess that the suggestion is the murder of Duncan, and that Macbeth's speechless, not only because  of the gravity of the suggestion, but also because it's almost as if he's had his own thoughts read:  he has already considered murdering Duncan.

3 Macbeth is blind to the obvious.  He ignores Banquo's warning: "oftentimes, to win us to our harm, / the instruments of darkness tell us truths, to betray's".  He should realise that no good can ever come from evil and yet he says: "This supernatural soliciting / Cannot be ill; cannot be good."  but it must be one of the two, and can only be bad as the witches are agents of evil.

 It is the same with the prophecies of the witches.  If only Macbeth had not been so blind he'd have seen that they had a double meaning.  He's blind to the obvious because he chooses to be so.

4 He is blind, and chooses to be so, because of his "vaulting ambition".  His ambition knows no bounds and makes him dissatisfied.  His ambition is fuelled in large part by jealousy - demonstrated when Duncan makes Malcolm his heir, this spurring Macbeth to say of Malcolm: "That is a step / On which I must fall down, or else o'er leap."

5 Although we see Macbeth as totally ruthless, in the past he also has had another side, which lady Macbeth refers to when she says of him that he is "too full of the milk of human kindness." although we see nothing of this in the play.

6 Macbeth is not without a conscience.  He does worry a great deal about murdering Duncan and he does realise that Duncan is a good king.  He realises full well how heinous is the crime he is to commit.

7 Macbeth, the man of action, is not too good when it comes to being faced with a decision.  He has not totally made his mind up when it comes to murdering Duncan, but it is finally made up by Lady Macbeth who ensures that he does commit the murder.  He allows himself to be bullied.

8 Macbeth is vain.   While trying to persuade him, Lady Macbeth calls him a coward (Act I sc vii) and he immediately replies:  "Prithee peace. / I dare do all that my become a man." but she's hurt his vanity / pride and the soldier in him hates to be called a coward, and so he unthinkingly does her bidding.

9 Macbeth is to be pitied.: he immediately regrets killing Duncan, saying of the knocking on the gates: "Wake Duncan with thy knocking: I wouldst thou couldst."  He is also fixed on a course of action over which he has no control.  He kills in increasingly greater numbers and he realises "I am in blood / Stepp'd in so far, that, should I wade no more, / Returning were as tedious as go o'er"  Events never turn out as he wishes, and at the end he is reduced to the level of a beast.