Among the female leads in Im Sung-han's dramas, Jang Seo-hee seems to have the best acting skills.

Actresses from the early days like Kim Ji-soo or the middle-aged actresses are good at acting, but
because of Im Sung-han's unique dialogue, you can see the shadow of the writer in the other actors. Since the lines are so distinctive and the settings are so unusual,
you get a vibe that makes you think, "Oh, this is an Im Sung-han drama," just by glancing at it.
But with Jang Seo-hee alone, you don't see Im Sung-han; you only see the character.
They say Jang Seo-hee acted with real grit... even in the useless scenes in "Brilliant Legacy," her acting was truly great.