I didn't read her other stuff until I was an adult. I started the Crestomanci series to see if my godson would like them and ended up reading the lot.
Howl's Moving Castle is a book I've owned, but had never read, much to herefox bewilderment. I read it after I saw the movie and loved it. It now has its place on my ipod, and I listen to it from time to time.