Chapter 3 - the final chapter - is in the form of a song. It is a song of worship and remembrance on the eve of national destruction. Habakkuk experienced the revelation of God and it changed everything for him. He still could not have rejoiced in his circumstances - present or future - but he chose to rejoice in the God of his salvation.
I would encourage you to work through this little book. It is a smaller version of some of the larger prophecies and it comes to some of the same conclusions as books such as Isaiah and Jeremiah. God is sovereign. God is working out the best for His people. Our response must be humble confidence in God's promises and quiet submission to His purposes.
But we get to sing!