I'm a huge fan of Orson Scott Card so it's not surprising that I enjoyed this book. What made it most interesting to me was that it's about Sarah, a historical biblical figure. I love the Book of Genesis but the lives described in Genesis seem so alien that I've generally found it impossible to take any of it seriously. Card manages to stay fairly faithful to the text, and by creating characters that you can empathize with, makes Genesis believeable. The whole issue of Abraham claiming Sarah was his sister to the Phaorohs, and having children with her handmaiden because she wasn't getting pregnant - it made me dislike Abraham a LOT and pity Sarah. But Card weaves stories around these events that make them plausible and has characters that are both moving and likeable - it's fantastic. (In that way, it's similar to his book, Saints, about the beginnings of Mormonism with Diane and Joseph Smith)
If you like Card's style and ethics and are in any way interested in the Bible (and how could you not be?), I'd recommend Sarah - and I'm looking forward to reading Rebekah, because making her story appealing seems VERY difficult.