Figure Analysis
Hezekiah is a very decent guy. He may not be King David, exactly, but he's definitely not one of those kings who starts worshipping idols or making any typical mistakes that then lead to a massive comeuppance. He's a righteous King of Judah, one who has cleaned up the Temple, removing the idols and restoring the worship of one God. At the same time, however, he makes big mistakes: he stops paying tribute to Assyria and makes an alliance with Egypt. That's a move that leads to a massive Assyrian invasion. But since he transfers his trust to God in the end (rather than to his Egyptian allies, who don't come through), it ends up turning around for him. God's angel slaughters 185,000 Assyrian soldiers, and their army is forced to retreat and abandon their siege of Jerusalem.
Hezekiah's righteousness is amply rewarded by God. Because of his humility and his faith, God saves him on what seemed to be his death bed, granting him another fifteen years of life. God seals this promise by turning back the shadow on the sun dial by ten degrees. Now, you might think that this would knock the earth off its axis and destroy all life on earth. But c'mon, this is God. He can calibrate that stuff.
And oh, one more thing: Hezekiah's name means "Strengthened by the Lord."