Maybe the plot development is a bit confusing or the character designs don't appeal to everyone. It could also be that the story pace is off for some readers.
Perhaps there are issues with the consistency of the world-building or the way the relationships between characters are portrayed. Also, the level of drama or comedy might not hit the right mark for some.
Could be various things. Maybe the storylines are too predictable, or the romance aspect isn't developed well enough. Different people might have different complaints about it.
It could be that the themes or messages presented in Secretary Kim manhwa don't resonate with some readers. Or perhaps the way the story unfolds doesn't meet their expectations.
One key feature could be a strong female protagonist who is the secretary. Maybe she is in a difficult situation in her workplace or personal life that forces her to escape. Another might be the settings, perhaps it's set in a big corporate world full of power struggles.
Women who can relate to the struggles of a working woman might be interested. They could see themselves in the secretary's situation and be inspired by her journey of escape.