Spoiler Alert...kinda
I give it a solid 3. It started off really good and quirky and I was grateful they didn't drag out the reunion with Nam Soon and her birth family. I seriously wanted a dramatic character arc with the villain to happen sooner because he is the finest thing in the show and I'm currently watching Lovely Runner where the chemistry is off the charts! About halfway through, I really didn't understand why all these seemingly smart people lacked discretion when it came to sneaking around and getting information. The mother would just outright confront people with her suspicions with zero tact or guile. Nam Soon was the most careless "spy" on the planet and would have covert conversations in the stairwell of the place she's spying at. Like, GIRL!!! If you don't send that man a text. Si-O had zero reason to trust Nam Soon because she kept getting caught doing stupid stuff. I did like the romance with the Grandmother and her boo. It was cute and fun and I'm glad they highlighted it because that was the only real chemistry in the whole show. Based on the description, I didn't expect it to be a sequel to the original so the cameo was a nice treat. Overall, I thought it was meh.
Afterthought: Everyone keeps saying Nam Soon should have been more compassionate towards Si-O like he didn't try to murder her whole family. It's less believable that she was able to be all smiley and fun around him for as long as she was. Also, I really hate that they cut her hair because the only bit of potential chemistry between the ML & FL was when her hair was long and wet fresh out of the shower and "Home-Sik" was clearly liking what he was seeing. ☺️