That one and The Crystal Cave are my favorites so far, despite the romance; I also like Nine Coaches Waiting. The one with the woman who inherits the cottage and gets entangled with a coven or a local witch or something like that had some nice writing but I thought the plot was dumb (don't remember exactly why, but I usually dislike stories about covens), I didn't like the subsequent Merlin books as much as the first, and I haven't read the others yet.