First series of Esther Yu, now I'm really wondering why she is so famous with that kind of acting skill?

About the series:
1. 1st episode is very boring and not clear of what the series going to lead us to.
2. The next 10 series are quite entertaining with the humor and fast pacing story lines, but then afterwards the stories become dull and boring.
3. It is strange to have a so called "heroine" who can't or never fight at all ==> referring to the main female lead, whose facial expression is very dull and only able to act cute
4. second male lead acting also not great, flat facial expression and no chemistry with the second female lead

Overall, I do enjoy some part of the series, especially the beginning, but afterwards the story lines just draggy and acting from the main actress really lame make it quite difficult to watch.

No offense to Esther Yu hard core fans.. this is purely my personal opinion. I shall see her other work to make sure whether she can act or if this is her character in this series.
But looking at the background of her character, she is not supposed to be a "cute" person, from her modern era character she is not with that cute personality, why suddenly when she become the heroine character in the novel she become overly unnecessary "cute"? (to be precise : tried to act cute, but does not cute at all)