Sonya Chung is by far one of the best teachers I've had at Columbia. The reading she assigns is a truly varied cross section of modern literary short stories, and she really knows her stuff. She's able to provide insightful comments on the reading and get students to think about it in ways they might not have otherwise. She's also a careful reader of student work. I don't think I've ever gotten more helpful feedback on my writing than I did in her class.
Sonya is tough and she will not let you get away with anything. If you're trying to coast and looking for an easy A, do not take this class. Things must be handed in on time in hard copy form, you may not be more than five minutes late to class (two lates are counted as an absence), you may not have more than one absence or it will affect your grade (she will never excuse more than one absence), and if you haven't done the reading very, very closely, she will know about it, because you will bomb her weekly quiz (Sparknotes will not help you here).
If you really care about your creative writing and want it to improve, this class is well worth the challenge. Sonya doesn't give busy work. You will benefit from every ounce of effort you put in.