The pace was good, even though it's difficult to fit a whole webtoon into 13 episodes.

Spoiler alert : We will be getting a 13th episode on Saturday!!

The acting was incredible, and the relationship dynamics were good. I love the OST too; listening to some of the songs, like Star by Colde, triggers my tears instantly.

With episode 12 you may feel that, The only downside you can think of is how, by forgetting her past lives, Ban Ji-Eum forgets her current life. and hasn't remembering her past 18 lives shaped who she is and her personality? Or maybe personality travels through reincarnation, whether you remember it or not. Either way, I won't mark it down for that being unrealistic, as remembering your past lives is already unrealistic.
But in episode 13 there is a twist!
I recommend it to all!