So many people seem to have liked The Tombs of Atuan best when first reading Earthsea, and I'm definitely one of them. Indeed I don't think I've read any of the other books more than once, but I read the tombs section (i.e. until they escaped) repeatedly. I think - though in many ways the books couldn't be more different - that what grabbed me about it was the same as grabbed me in She, the creepy atmosphere of the underground labyrinth/city/tombs.