He s won the struggle with himself. His human and virtuous impulses won out over his animal and pernicious urges once all the parts were known and accepted. The rarer action is in virtue than in vengeance. Now Prospero is still not a perfect man and the world is not a utopia in a golden age as Gonzalo idealized in Act II, scene 1. Caliban and Antonio had to be forced into submission.
Anarchy has to be kept at bay.
Though there was clear growth for Ferdinand, Miranda, Alonso, Ariel, Gonzalo and Prospero, there was only grudging repentance from Trinculo, Stephano, Sebastian and Caliban. There was silence from Antonio. For you most wicked sir, whom to call brother would even infect my mouth, I do forgive . Trouble can still reappear. Prospero, if not careful, might have to take another trip to the island.