So far, they've kept fairly close to the original storyline, though some of the details have been changed to add more drama to the TV series. They added some things that wasn't in the webtoon, like the camping trip and the judo lessons, which I liked since they helped better connect the storyline.
The acting is fantastic, but I particularly like how they went more in-depth with Jiwon's mental and emotional state. Like, she initially wanted to run away, but then decided to get back at her AH boyfriend and BFF. But as she continued with her plan, she starts to realize that when she changed the course of her life, it doesn't just affect her, but also the people around her. She also had to relive a lot of painful memories from her past life, and while they showed that in the webtoon, the TV series was more hard-hitting.