I so agree with everyone else that Ming Dao and Joe Chen look better together.
However as much as I do love Mingen from Prince turn into Frog, I have to say that I am glad that they chose Ethan for this role. After watching the episodes I honestly cant imagine anyone else playing the role of Cun Xi. Ethan really brought to life the character of the arrogant , sheltered (never had a fight in his life), slightly immature, but still can be sexy Cun Xi. I believe the initial contrast, in both the way they dress and the vast height and build difference between them at the beginning works to their advantage to emphasis their physical incompatibility. Whereas in looks, I reckon that Ming Dao and Joe Chen look quite compatible already... and I can totally see Ethan with someone who is tall and elegant like his current real life girlfriend Tiffany. Critically speaking I don't find Joe Chen conventionally good looking, she is more cute and innocent to me. However it is through her kind nature in the series that her character begins to blossom and become more beautiful in the audience as well as Cun Xi's eyes. And that I believe is the true beauty of the series. That the prince in fact, dumps the tall and lithe Odette and falls for the ugly duckling. It is not necessarily her new style that he has fallen for, nor is it her brand name clothes, makeup or new found talent. Rather all those don't really matter. Perhaps she is still the ugly duckling inside but to his eyes, she had long transformed into a swan.