I love the realistic approach this drama takes to relationships and people's thought processes. I truly appreciate the webtoon writer's efforts to depict the feelings that come into play for every decision a character makes, and so accurately and realistically at that. I'm sure it must have taken a lot of analysis and an extremely high EQ. I did not read the webtoon but I do know the full story. Since the show is so well-made and seems to stay true to the original story-line, I have decided not to read the webtoon, but I am currently enjoying another work from the same author and I see the same qualities in this other webtoon as well (read Daily JoJo, it's just as good as Yumi's cells).
OK, now off with the review we go:

STORY:
The story is literally the best and most realistic one among all the KDramas I have ever watched. It makes you relate to and agree with the FL so deep. Honestly, I didn't want to watch the drama at first because of the cells (I was like: Animation?! Really?!). But man am I happy not to miss out on this amazing piece of work, ESPECIALLY the cells. They might be animated characters, but they are what makes the story so realistic. They let you decipher every feeling and thought the characters have, and they do it in an adorable way. I don't want the review to contain any spoilers so I can't give you examples, but if you have ever dated before, you will find yourself relating to the characters and enjoying the cell village the most.

ACTING/CAST:
Honestly, nothing was outstanding about the human characters' acting. The roles were not that challenging. However, I still loved Woong and Yumi's chemistry. They reminded me of my bitter-sweet memories of me and my ex. What I truly enjoyed was the voice actors' performance. It's really hard to hook me up to animation characters, but the voices were well-casted and well-performed, especially the emotional cell. All in all, I enjoyed the acting enough, and I'd gladly forgive any acting/casting shortcomings for the sake of the story.

MUSIC:
I always say in my reviews (not that I have written many of them) that I have a pretty particular taste in music and my opinion doesn't really count in that department. While none of the OSTs made me go back and listen to them, I did find them well-aligned with the mood.

REWATCH VALUE:
I can say with confidence that I will go back to this drama multiple times in the future, especially when the 2nd season (and hopefully the third) come out. It definitely is worth the time.

OVERALL:
I give this drama an overall score of 10 because the story matters to me way more than the acting and the music. I loved it and enjoyed it to my heart's content. Hope you all enjoy it as well...