Unlike God's anger, Jonah's anger had nothing to do with the wickedness of the Ninevites. Because a man's anger is often unrighteousness in its administration. His imperfect knowledge prohibits the righteous administration of anger. That is, we do not have enough information to know first, if our anger is justified, and second, even if it were justified, how to properly work out righteous retribution. Because a man's anger often controls him rather than being controlled by him.
Anger can control one's thoughts to the point of irrationalism.
Anger can control a person to the point that he takes unreasonable action. Jonah left the city and built a shack so he could wait to see what would become of the city. Because a man's anger causes Him to question God's righteousness. Jonah obviously thought that God was acting incorrectly in sparing the Ninevites. Therefore the Bible gives us warning after warning, telling us that it is best to simply put it away from us.