Ruth and Esther depict more than the struggles of two women. The authors show God's work at different times and in different ways. Ruth is covered as homiletic exposition, while the commentary on Esther breaks down historical and political nuances to show how events providentially came together to bring about salvation.
I learned a lot from and enjoyed the Ruth portion of this commentary. But their ideas on Esther, right from the start, came from such an outlier perspective that it was hard for me to take the back half of this book seriously. While the view they ascribe to is offered as one of the possibilities by other scholars, those others are careful to point out it's only one of many possibilities, since the text itself leaves many questions unanswered and submits many facts without comment on their morality or wisdom. (A technique that points us to the true key player in the story.) The authors' adamance hurts their argument.
If you're looking for thoughtful, careful, readable commentary on Esther, I highly recommend Debra Reid, Joyce Baldwin and Karen Jobes.