Among fairy tale worlds, there are different styles of fairy tales world. This is the sort of world where wizards and wizards are just accepted parts of the landscape (and the subjects of gossip), magic is commonplace, everybody knows the expected tropes, and nobody's really surprised by anything. In a word, it's a comfortable fantasy world with a few uncomfortable characters, one of them being Howl, who lives in a moving castle.
Not surprisingly, Sophie winds up inside the moving castle and proceeds to make herself useful by using no magic at all, much to the consternation of the lady killer Howl.
Wynn tells her story as a series of vignettes and moments, wandering through the tale with little attention about where exactly it is right now, instead providing sufficient entertainment, whimsy, and delight to keep you moving along with the story anyway. Yet, despite all the magic, it's not a story of high magic, but of high heart.
I did find that the subplots got just a little too busy. Towards the end, I lost track of who was enchanted with what and how, so I lost some of the book's effect in sorting out the fast approaching ending.
Like all fairy tales, the book ends with a happily ever, but only after after taking you the long away around to get there. It is a fairy tale, after all.