I was promised a dark, gruesome revenge drama where the FL spent 10y+ planning how to hit back the perpetrators who provoked her such intense pain during her teenage years and left marks deep enough to push her to suicide, so she has no limits and boundaries when it comes to what she would do for revenge.
What I got was a moderately entertaining drama whose value consists in the gorgeous acting of the villains and the heartwarming subplots of the side characters. The main issues I noticed within this drama were:
1) LDH's character was pretty much out of place for this entire drama (and I LOVE LDH, so this was particularly disappointing for me); it's like the writer was following the drama recipe where there needs to be a male lead obsessed with the female lead that she can count on, so they just added him into the mix and tried to add a backstory that would link him to the revenge plot, but it just felt overall out of place and not fitting with the rest of the story; the romance was also unnecessary, but I didn't particularly mind it;
2) not much emotional expression from SHK; I was really contemplating for a while whether maybe I'm just biased based on her previous dramas and this is just how her character is supposed to be, or whether her acting was really lacking in this drama as well; what made me lean towards the second option is that the actress who played the younger Moon Dong-Eun really KILLED the role and made me feel her pain and despair and consuming need for revenge in every moment, which I didn't really feel with the adult Moon Dong-Eun;
3) not that much.. revenge? almost all the villains' "punishments" came from their own doings and 'karma', I didn't feel like the FL did much to inflict pain upon them; this is not inherently a bad thing, but it didn't feel satisfying to me because I thought that the FL would have a more active role in taking revenge against these people, but in the drama she just played some strategic moves and let them push each other to their own downfall; again, this is not a bad thing, but it ultimately felt unsatisfying to me because I felt like I was promised cruel, merciless revenge and what I got was just the mere consequences of the villains' own actions, without SHK playing a significant role; this, combined with the acting points I've mentioned, made the villains' characters shine the brightest in the whole drama, while the FL was pushed sideways and wasn't in the center of storyline; honestly, I feel like if they removed the FL and ML, the drama would've been even better, the centerpiece was the villains' terrifying actions followed by their well-deserverd fates provoked by the consequences of their wrongdoings.

Overall, I can't say it was a bad drama, but definitely not a masterpiece and it didn't feel satisfying enough for me to even call it a "revenge drama". It's a decently entertaining watch though.