She is more righteous than I: Judah admitted he had failed to provide an heir. It was wrong for Judah to visit a prostitute, but Tamar had a legal right to have Judah's child and acted on it.
In the book of Ruth, the elders gave a similar blessing at the marriage of Boaz and Ruth. They prayed that God would make Ruth like Tamar (Ruth 4:12; compare Matthew 1:3, 5).