2:1-5 offers a preview of the whole book.
The Judges Cycle (2:10-19) is repeated a dozen times.
The primary picture shown by the book is what life is like for the People of God APART from God.
The choice is laid out so clearly. Remember Joshua's last words to the people; "Choose this day whom you will serve . . ." Judges offers the picture of choosing wrongly.
Judges also shows the heart of God toward His people in repentance. The amazing thing is not how often they fail, but how often God forgives!
The collection of stories are pretty graphic and there's rarely a clear picture of who is the "good guy". The moral of the stories is this: there is only one Good Guy-- the Lord.
You can choose life your way, or His way. You choose.
The last verse of the book sums it up. "In those days Israel had mo king; everyone did as he saw fit".