10/10 for plot, i love love this concept of having an app that shows whether or not you like this person, its so cool
But with that said, i hate the characters so much (read the most upvoted review i agree with him/her so much). There was a lack of character development and felt that more couldve been done to allow viewers to understand the characters more so we could understand why they make certain decisions. Hopefully, these will be addressed in season 2.
The actor acting as sun oh also has very awkward acting? i feel super uncomfortable watching him during the whole of 8 episodes.

Although there were these problems, 7.5/10 might rewatch it because it has few episodes and i really like the concept of the app.