Take all the well-known tropes (or plots) from soap-opera like dramas, add convincing acting from a good cast, season with enough budget to do a quality production based on a well-written script, and you get what feels like a high-quality soap opera on steroids.
You could also say this is another "poor girl, rich guy" kind of story, or a take on the "Cinderella genre".

Very brief synopsis:
Han Yi Joo was at a young age adopted into a family, where she was mistreated. As an adult, she found out that her husband was in love with her sister, and her stepmom framed her for her own wrongdoings. HYJ then dies after a car crash, and wakes up as herself a year previous, right before her wedding. She wants revenge, and as the first step, she brakes off the engagement, and then approaches the man her sister had her eyes on, a CEO from a powerful family; Seo Do Guk. He takes her up on her initiative, and they enter into a contractual marriage. His reasons for agreeing turns out to be more than her promise to help support his business dealings, and as secrets and evil acts gradually comes to light, will love also find a way to thrive?

The story is well-paced and balanced between giving you some breathers in between the events propelling the story forward. And although you have all the familiar elements present (scheming, villainous characters, half-siblings fighting for power and attention, business rivalry, one night stands and consequences), it is executed without feeling like cheap tricks. That said: 12 episodes of about an hour each felt like the right length. Much more, and it would have been dragged out, and any less would probably have felt rushed. Even if it is well-written, I am only giving 7,5 stars for the story, as it isn't very original.

I love Sung Hoon as the ML, and Jung Yoo Min in the FL role. The both deliver solid performances, building a connection with the audience. I could sense his sympathy and love, and I felt her deep sorrow and anger.
As for the supporting roles, the cast for those were also very good, and I found especially Han Yi Joo's stepmom and sister to give convincing performances.