1. Great chemistry between the main leads. Their love is quite wholesome, also there's a fair share of fluffy moments
2. The plot isn't draggy and there's indeed some mystery around the antagonist
3. Flashbacks are a nice touch and complement the story just well
4. Side stories are done well. Compelling but do not drag the attention away.
5. The theme song is superb
6. 8 episodes x app. 30 minutes - perfect length for binge-watching

Characters:
I think the cast was well selected. The FL is cute, the ML is definitely dashing. They make the classic match. She's nice and trusting, but not a doormat. She believes the male lead but does not let him walk all over her. The ML does have his moments of love-duty hesitation, but is overall wholesome. There's a satisfying amount of fluffiness ;)
The secondary couple was ok. The antagonist did a nice job, too.

Story:
What is so "mysterious" about the story? 1. The way the leads met. 2. Who's the bad guy. Is there more than one? If yes, who is the mastermind? It's not god knows what, but it does keep your attention until the end.

Music:
The OST wasn't particularly memorable. But the theme song definitely did the job.

Rewatch value:
I'm giving it an eight only because of "the couple moments". (Again congratulations to Yilia Yu and Tsao Yu Ning for the nice job!)