I think the plot and everything was amazing. But hear me out.
In the end, It felt like the final shot ruined the whole purpose of the show. The lesson we learn is that "revenge brings more sadness and grief / pays a price".
I just felt like the character of Ji-woo should have been dead at the end. While leaving the cemetery, There is seen a slight smirk on her face, which shows us her "defeat" but it only gave the wrong idea of " you will feel great after revenge" or something along those lines.
As much as I loved Ji-woo, she probably should have stayed dead to portray the proper message better.
(pls don't come at me its just my opinion but feel free to argue)