Prince Ferdinand is Alonso's son and the heir to the throne of Naples. He is quick to love, and seemingly quick to forget his father's "death," but it does seem that his heart is true and his affections, though quick, are genuine. He does have a sort of princely arrogance about him. (He may be a prince, but a little humility never killed anybody.)
We learn about Ferdinand mostly through his efforts to gain Miranda from Prospero. Ferdinand is happy in his labors, blinded by love, and quick to promise the title of queen and wife to a girl before he even knows her name. He also vows to stay true to her father, Prospero, and not violate Miranda's chastity before their wedding night—maybe because he's a good guy, maybe because Prospero threatens that the heavens will rain down fire and brimstone on him.
You can't say much about Ferdinand because he doesn't say or do much, besides mooning in love. Still, he does seem easy to love, earnest, and good above all else. (And we needed a little bit of that in the play, didn't we?)