The slip cover properly brings to mind dime novels of the exploits of the midwest, though I am sure future books will hold more exploits of the wild west than this first one. The book follows Eff, a thirteenth child (and therefore bad luck) and her twin, Lan, the seventh son of a seventh son (which, as any mythologically minded person will know, indicates good fortune and talent). Wrede skillfully blends magic and the frontier, creating a world as rich and believable as the Enchanted Forest.
I think the optimal reading range for the book is 3rd through 7th grades, though anyone who loved the Enchanted Forest Chronicles or, indeed, Little House on the Prairie, may wish to pick it up. Middle and High School readers may also wish to pick up Wrede's Book of Enchantments (collected stories), Mairelon the Magician, and The Raven Ring. Keep your eyes open for the last two- I believe they are out of print.
Okay, I have now tooled about Amazon and come to the conclusion that college makes you horribly unaware of too many books. More specifically, Wrede's The Seven Towers, Snow White and Rose Red, and Caught in Crystal, many of which were originally published in the 80s and only rereleased this year. Approximately half of her novels are out of print, so keep your eyes peeled at the library and used bookstores. My library surprisingly had a number of these out-of-print lovelies and so I can recommend them whole-heartedly.