JJH looks so awkward and stiff inhabiting the character of Kuwano which Abe Hiroshi pulled off so well. And the scenes seem so much more exaggerated for dramatic effect in He Who Can't Marry than the economical, subtlety portrayal of Kekkon Dekinai Otoko. Well, I guess it's just my personal preference for Japanese production which pretty much reflects the nature of its culture and people.
It's hard watching the Korean version when it duplicates much of the Japanese drama and well yeah, I love Ken-chan more. Those expressive, inquisitive and knowing expressions!