My young browser grabbed this off the shelves in the Children's Room. Published by Candlewick Press, this "Genuine and Most Authentic Guide" to chivalry bears an "Ages 3 + up" notation on its colorful and nicely-illustrated cover.
We loved it, but my little squire is 5 and a lot of it was over his head. He didn't care, though, and neither did I. It took us a couple of days to read at bedtime--there are several chapters and a lot of information displayed on each page.
The book is full of pop-ups, pop-outs, text boxes, mini board games, books-within-a-book: it was not the most relaxing bedtime read, but it was completely engrossing. The illustrations are charming and engaging. The book explains the fundamentals of chivalry while taking the reader on a quest to rescue Sir Geoffrey, the author. It does address the reader as "my son," which does not recommend it if you're reading to a girl. The text is full of humorous asides, like this one in the chapter on Questing: "Make sure the dragon you are going to fight is actually wicked and not just misunderstood. Many people quite like them." The book also contains a greater message about chivalry in everyday life--be brave, stick up for the defenseless, never lie, be generous, etc. (Surprise Bonus for former medieval lit majors: the book contains a terrific little recap of the medieval poem Sir Gawain and the Green Knight.)
Bottom line: very enjoyable. I'd put it at ages 5 + up, and I would not put it in the hands of a child who is too young to treat books gently.--Juno