First of all, this kdrama has next to no connection to the classical American novel of the same name. It only loosely based its characters on it, namely - the three poor sisters, their rich great aunt and a male friend of the family who simps over one of the sisters. The rest is pure fiction with popular contrived tropes used in kdramas:
-evil chaebols;
-corruption;
-secret organization with unlimited power;
-off their rockers villains;
-makjang.

PLOT:
The first half of the show is great and promises a potential masterpiece. It starts fresh, with relevant topics raised about poverty, social issues and is mixed with murder mystery. Every episode manages to rile up new emotions in the audience with unexpected plot twists and sympathy for the characters suffering injustice. Small niggle starts to appear with the introduction of the conspiracy theory trope - the powerful secret society (#Illuminati), and fantastical properties of blue orchids.
And after a shocking finale of superb episode 8 it rapidly starts to go downhill with reveal that the main villain is just a deeply deranged person who likes to play with the victims before killing them. Absurdity, increased usage of makjang tropes, dumb circus and public shows are introduced in the next episodes until it all culminates in a cringey finale where none of the villains get what they deserve (they all die instead of rotting in prison for their crimes) and little women get what they deserve (money!) but at the cost of other people's fortune.
The tale of the ill gotten money, that is the catalyst of this whole plot, is a long winded one, but in the end the three sisters get their hands on it with the help of ML, even though originally it belonged to the victims of the bank made bankrupt by the villains.
The final message was supposed to be that ill gotten money is evil, it's not worth chasing if it costs someone's life, better live in honest poverty than dead or rotting in jail. But that message is completely negated by giving said money to the sisters anyway in the end. The hypocricy is apparently lost on everybody in the end, because that's where the show conveniently ends.

CHARACTERS:
First of all, lead female characters here are deliberately made dumb, flawed and reckless. It was script writer's conscious decision as was reported in the interview with her.

The dumbest of them all is the bookkeeper eldest sister, who throughout the whole drama made only 1 smart decision (to swap the cash with bricks), the rest was sheer luck or help from other characters. But what her character lacks in intelligence, is compensated by her love of her friends and family. She manages to forgive and save her friend, who basically set her up big time and put her in great danger, from certain death. And she'd do absolutely anything for her sisters. Being poor through all her life though, her next greatest love understandably is money and she makes a lot of stupid mistakes after a very large ill gotten sum of it is suddenly left to her as a gift. But stupidity must be punished, so in the end her character does suffer a bit to reflect on what she did wrong according to law. She's rewarded with her material dream by the end of the show.

The reporter middle-sister is a bit smarter than her elder sister. She is self righteous and claims to have unbending integrity and high morals, but they are heavily tested as her sisters get themselves in trouble and lawless methods that villains use make her fail to expose them again and again. In the end she succeeds in her investigation and gets together with a male long time family friend who helped/followed her throughout the episodes. However their romance from friends to lovers is very weak and that male character is one of the most useless in the whole drama.

The youngest sister is the epitome of a teenager during "a phase" - an ungrateful little brat who throughout the whole drama never once said a grateful word to her sisters who'd do absolutely anything for her. Instead, her grand plan was to get away from her poor family and get rich and comfy life quick by befriending the villains daughter. And she did succeed in that in the end without too much of a hassle, so I guess she was the smartest of them all. Some people claim that she did thank her sisters in the end by getting each of them a share of that ill gotten money. But she didn't actually, it was all ML who just accidentaly met them running away and decided to use her friend's account for a while (though he could have as easily have done it by himself). In the end her role was downsized to a minimum, a pretty selfish and consistently ungrateful character, who just had to be there because there had to be 3 sisters.

The villains of the evil secret society were several, but in the end only the main one is worthy of note. The society itself turned out to be not as powerful and omniprescient as was advertised. It's a drama about women, from women's perspective and so the main villain is also a woman. Her character development from a prim and proper house wife, that stands in support of her brilliant husband, to a crazy deranged psycho was entertaining to watch, but in the end, after her husband died for the cause, her house of cards crumbled easily and the final showdown with her was a total cringefest on par to the cringiest of the makjang dramas out there. Guess her character wasn't smart either without outside help.

And lastly whom I'd call the real main hero of this whole drama, the male lead, the guy who will give you major trust issues trauma throughout the episodes, the mysterious, the most confident and smartest of them all, the man with the plan - Choi Do-Il. He was a real safe haven of rationality and smart decisions in this drama plot's sea of random dumbassery and craziness. Probably the most favorite character of them all in this drama.
Of course, there was also his cool and badass commando father, but he was conveniently swept under the rug and forgotten about in the craziness of the last episode.

PRODUCTION VALUE:
It was excellent and just screamed quality. Cinematography was one of the best I've seen in kdramas, very well made.
Music was also very good and catchy.
Actors work overall was great as well. Kim Go Eun finally landed a role she was not a miscast for. The villains actors were absolutely infuriating to watch, they did really great, loved to hate them.
The only one who I think could have done better was the youngest sister's actress - Park Ji Hoo. She was too stiff and had samey facial expressions all the time. But since she's an underage noob I'll give her some slack.

Overall, it's an exciting and flashy drama, that reveals one shocking and unexpected twist after another at a breakneck speed, hoping you won't notice plot holes, dumbassery and shallowness under the surface. And introduction of certain badly chosen cringey tropes in later episodes ruined its twisted mess of a plot in the end. Could have been a true masterpiece otherwise, a shame. I give it a generous 8 out 10 overall.