When I saw two negative reviews, I had to respond, especially since I could very easily see a doctor closer to where I live or work, but choose Dr. Tan. (Also, she is Ling Tan, not Tan Ling.) I'm relatively picky about my doctors, so the fact that I have stuck by Dr. Tan should speak volumes about both her professionalism and her abilities.
I have been seeing Dr. Tan fairly regularly since before 2007. She is extremely thorough, and really listens - the latter a quality lacking in many physicians today. She also makes referrals when necessary, including one time sending me immediately to the emergency room for a health matter that, if left untreated, would have killed me.
Furthermore, her medical knowledge is good. Again, when something lies beyond her expertise (i.e., when one's condition merits a specialist), she is quick to refer. She also will refer when requested.
I unhesitatingly recommend Dr. Tan.