The fourth was very much a purposeful departure I think from some of the things Le'Quin (in her very trademark round about way) has said. The books are supposed to show going from childhood to Adulthood to some extent which does mean putting away childish things, which is of course a hard and depressing thing to do. It was definitely a much harder book to read but still very good and moving. I haven't read anything else she has set in this world (is there anything else you seem to imply their is). Much of her other work though is just as good but much more in the style of the fourth. Le'Quin is not a very "happy" writer often. Comes from her Taoist beliefs I suppose.