To be honest, people are being too harsh on the drama although I haven't read the webtoon. I would be lying if I said i didn't watch this kdrama because of Song Kang, and it's true that the cast was better than the story line itself but I think it's fundamental to understand the fact that it's a friends with benefits plot/"girl is devoting her time into another red flag" and perhaps that might not be everyone's cup of tea which is probably why many don't like the drama.
I wouldn't say it's trash because personally I completed it and in fact re watched it. It's not a waste of time if you actually try to view and understand each character and their love lifes . It is different from your other romance collage plots but it's fun to once in a while watch something distinct, and also if you like the cast it's a big plus, because I think what really helped me get hooked on the plot and the show was the acting and the actors. If that's not what you're looking for, pretty understandable.

Also a plus, I loved the OST it encapsulated the vibe of the drama really well and gave it some good atmosphere.

Overall, I don't hate or dislike this drama, I think there's no such thing calling it a "disappointment" or a "waste of time" (at least in my book) so if you're looking for a spicy and fairly realistic plot, watch Nevertheless.