This is a story that is basically about "be careful what you pray for - God may decide to give you exactly what you asked for"
Israel has been governed by judges for about a generation and they look around and realize that all of the other nations have kings. So Israel says - "hey, we want one of those too, that's what we need to be a real nation"
God says - no, you don't really want a king - kings are more trouble then they are worth, trust me.
The people come back with - no, we really want a king.
God says - okay then, you want a king - here you go. And he gives them Saul - Saul is basically the definition of a bad king. He is immature, selfish, weak and a poor governor.
Be careful what you ask for - God may give it to you.