But oh lord, the covers have not served it well. Too much like a Disney princess film; medieval Vogue, anyone?; strange and dark rather than funny and lively. In fact the best version is probably the film poster, which shows Birdy as a live, warm, breathing human girl.
It's interesting to compare Karen Cushman's novel with Kevin Crossley-Holland's Arthur diaries, set about a hundred years earlier, with the same conceit. Many of the details of daily life are similar, though as a boy and a squire, Arthur's experiences are not the same as Birdy's, but the main difference is in tone. The Arthur books are beautifully written, but they take themselves more seriously than Cushman's. I think young readers would do well to read Catherine, Called Birdy first, and if they get a taste for medieval life, give Crossley-Holland a try.