Yes, this drama is definitely one of the most well executed drama the whole Korean entertainment industry has delivered,
Brace yourselves, this will be an essay.

THE STORY:
From the beginning to the end, I can effortlessly say that every second of the drama has placed great thought and effort into the its production. No filler episodes, no unnecessary subplots. You can pretty much expect to be on a roller coaster of emotions throughout each episode.

I've watched the Japanese version long ago, and I loved it as well. But It's pretty safe to say that the Korean version well surpassed it.
The Japanese version didn't show as much characterization between the abuser and the child, (probably mainly due to fewer episodes and less time) but the relationship between the boyfriend and mother of the abused child in the Korean version was heavily emphasized.

I absolutely love how the writers gave more back story to the ones abusing Yoon Bok because it gave the story just so much more depth. The abusers were written so well that I was able to in a way "sympathize" with them despite all the shitty stuff they have done.

The only thing I'd do without would be the slight romance between these two characters (not going to say who, but you probably already figured it out.) It felt slightly awkward but still, I don't mind it being there. It was still very enjoyable.

And omg, there are so many strong characters in this drama I'm cryingggg. I love seeing characters that fend for themselves, and not be a pussy relying on others all the time. Each and every one of them are well rounded, complex, and dynamic.

THE ACTING:
I cannot put this into words, you just gotta watch it for yourself how amazing the acting is by every single person in the cast.
The dynamism of Soo Jin's journey as a mother was very satisfying.

I especially loved how Kang Young Shin (played by Lee Hye Young) portrayed her character, and I think she is one of my favourites in the drama. I love how she is not perfect as a mother, but you can see her love towards each and every one of her child. She absolutely killed her role.

Yoon Bok (played by Heo Yool) is so wonderful and smart. Both Mana Ashida and Heo Yool are amazing child actors. The looks in Yoon Bok's eyes are so innocent and bright yet there is always that touch of melancholy hidden from the traumas she faced.

The emotions and relationship between characters are done so humanly and realistically, you'd start to wonder whether or not Heo Yool and Lee Bo Young are actually mother and daughter.

MUSIC:
I don't actually remember lols, but it definitely made a big impact on the mood when you are watching.

CINEMATOGRAPHY:
Expensive lenses. Love it. The washed out colours that are dull and gloomy really sets the mood.
Very high budget production that really gave out the cinematic touch which affected the emotional appeal a lot. Gave the whole drama a higher value with high quality cinematography.

The director, writers film crew, and actors worked so hard to deliver such a compelling piece. Definitely worth your time to invest into the story, and it's a heavy one for sure. No matter what type of drama watcher you are, this drama won't leave you without an impact on your emotions.