This is the first book in Orson Scott Card's Women of Genesis series, which also includes Rebekah and Rachel and Leah. It is actually the last one of the series for me since I read the others in 2006.
I think it is a good exercise to read about people in the scriptures as real people, with day to day lives, hopes and dreams, as long as you remember that it is just a fictional interpretation based on the Bible. The fact that Card and I share the same faith (and he's a North Carolinian) is nice, but I also love perspectives from other faiths such as Anita Diamant's The Red Tent.
Card chooses to portray Sarah as a strong feisty woman, deeply in love with Abraham. Sarah and Abraham do (gasp!) argue, since sometimes she has to tell it like it is while Abraham's head is in the clouds. Her devotion to Abraham's God is also an issue as she was raised to believe in a different God. However, her faith is strong and she always remains true. As you would imagine, her fertility struggle is a central issue and the portrayal of her relationship with Hagar was, for me, the most interesting plot line.