The Wonder Clock book has been a favorite source of bedtime stories for three generations of Leadley boys (my father, myself and and my son). It is best read (and read and read ...) from ages 7 to 10. The book contains 24 separate faux fairy tales that are just the right length for a 15 minute bedtime story. The short stories are bound together by a metastory of the "wonder clock" that whisks the narrator off to observe and recount the other 24 tales. Each story is preceded by a short, illuminated poem, starts with a scrollwork capital and contains at least two wonderfully ornate illustrations. DO NOT buy a copy of this book which doesn't contain the original illustrations! They are part of the "wonder" for young readers. The stories are set in the Middle Ages somewhere in northern Europe (¿Belgium, Holland or southern Germany?) and feature lots of minor kings, princes, princesses, woodcutters, swineherds, ruffians, rogues and magical creatures.
1) Although the Wonder Clock book can be read alone by precocious readers as early as second grade, I would recommend a joint reading the first time through with asides on morality. It is my belief that the actions in stories that feature villians being dragged to death behind wild horses, beatings, blindings, whippings, etc. need to be given moral context when a young child is first exposed to them.
2) I'm not sure whether this book would have as powerful an appeal to girls. Among us, my grandfather, my father and I have only raised one girl out of ten children (my aunt) and don't have much experience to offer. Upon reading the book again from an adult prospective, I've found the female protagonists (the wise queen, the wise princess, the magical Swan Maiden, etc.) curiously passive. Even Princess Golden Hair, who treks to the end of the earth in search of her beloved husband banished by magic, seems unassertive.
Conclusion: Kids, especially boys, love it. Don't feed it to them unadulterated :-).