For me, the most interesting aspect of the work is actually the background. I have not studied medieval Korean culture, and thus the cultural setting is exotic to me. I'm especially interested in the discussions of pottery as a craft, and its cultural role. The development of incised pottery is especially interesting, as is the method of transmission of innovations in pottery (although this is a novelist's view, not a historical one).
The narrative arc of the story, with the brave, good, clever young boy from the poor background who eventually wins over the embittered curmudgeon by his persistence and sheer saintliness of character strikes me as cliched at best. As is sometimes the case in young adult fiction, the characters seem almost stereotypes and the plotting predictable.
Tree-ear is an analogy for you or me growing up and learning to work through disappointments, negotiate change and achieve success even in light of challenges. Persistence will bring reward. When Tree-ear's internal desire to learn how to make a pot is not fulfilled immediately, he does not give up. He continues to do the job he is asked to do. Even to the point of being attacked while delivering some pots made by Min. He then returns to learn his guardian Crane-man has died and he is left alone. He finally is adopted by Min and his wife and learns to make pottery. I like the story, the idea of persistence and finally his reward does come. This is a great example of faith.