Like much of Shakespeare's Macbeth, the predictions and advice given to Macbeth by the apparitions in Act 4.1 are a mixture of opposites, as are Macbeth's reactions.
On the one hand, the First Apparition tells Macbeth to "Beware Macduff." But on the other hand, the second apparition tells Macbeth:
Be bloody, bold, and resolute; laugh to scorn
The pow'r of man, for none of woman born
Shall harm Macbeth. (Act 4.1.79-81)
And the Third Apparition gives Macbeth more reassurance:
Be lion-mettled, proud, and take no care
Who chafes, who frets, or where conspirers are.
Macbeth shall never vanquished be until
Great Birnam Wood to high Dunsinane Hill
Shall come against him. (Act 4.1.90-94)
Macbeth seems to react to the above by being reassured:
That will never be.
Who can impress the forest, bid the tree
Unfix his earth-bound root? Sweet bodements [omens, prophecies], good. (Act 4.1.94-96)
Yet, seconds later when the witches vanish and Macbeth finds out that MacDuff has fled to England, he announces that he will order MacDuff's family killed.
These oppositions contribute to the themes of equivocation and opposition in the play. Since the witches first introduce the idea of fair and foul being interchanged, oppositions abound. And the witches equivocate here as they do elsewhere in the play.
Macbeth's reaction also reveals that he is at least smart enough to know better than to place complete confidence in the witches, though he would like to. Repeatedly as the play progresses, Macbeth will one moment seem to believe he is invincible, while the next moment seem to know the predictions are too good to be true.
After the meeting with the witches in Act 4, Macbeth is far from satisfied. When they finish showing him the prophecies through the apparitions, the witches do a dance and vanish. Macbeth asks "Where are they? Gone?" And then he declares that "this pernicious hour/Stand aye accursed in the calendar." In fact, he tells Lennox who has just appeared that
infected be the air whereon [the witches] ride,
And damn'd all those that trust them!
By cursing the hour that he spent with the "infected" witches and damning all that trust them, Macbeth is disdainful and suspicious. He had gone to the witches wanting answers and directions, but now he is more confused than ever. The apparitions tell him to "Beware Macduff." But then they tell him that "None of woman born shall harm Macbeth." These two prophecies are contradictory, and Macbeth responds likewise. At first he says that Macduff should live, since he has no reason to fear him. Then he changes his mind and decides that Macduff shall die. When the witches later show Macbeth a vision of Banquo's descendants becoming king, Macbeth looks on in amazement. Macbeth now is not sure what to do next. He likes some of the prophecies, but wants to prevent others. Can he have it both ways? How can he believe the prophecies if he thinks he can change them?
Macbeth's next response shows his confusion:
From this moment
The very firstlings of my heart shall be
The firstlings of my hand.
His decision to kill Macduff's family and servants is that of a panicked man. He's angry and fearful and somewhat irrational. He acts impulsively, not prudently, as if any action is better than no action. And, as you know, it is this decision that instigates Macduff's vengeance.
The main thing that should trouble Macbeth after this meeting is the prophecy that he should beware of Macduff. That ought to make him worry. The other thing that could worry him is the parade of kings, though the meaning of that is way less obvious.
What should make him feel better is the other two predictions. He will feel good because it seems as if no living man will defeat him until the forest gets up and moves.
For the most part, Macbeth feels pretty good after this meeting. After all, he feels confident enough that he can go ahead and have Macduff's family killed, showing he believes he is invincible.