Production: For being low-cost I thought the costumes were well-made and high-quality, and I thought the outfits they wore looked cool. If they used wigs, it looked like they used a lot of hair gel, but the hairstyles were nice, and the makeup wasn't too over-the-top.
Story: I could tell the story was well thought out, and it requires a lot of piecing together to solve the mystery. I'm not big-brained enough to figure out who did what, but they explain the process after the big reveal. What I like the most about this series is the character dynamics; the main female lead is not helpless and plays a big part in actually helping the main male lead figure out the crime. When the characters get into misunderstandings, they are very mature about it and resolve it within the episode and aren't dramatic about it. The romance is a bit cheesy at times but it works somehow because the chemistry between the characters is adorable. The female leads work together and never get into big fights; the same thing is true for the male leads too. As far as I could tell, every episode had a purpose and there were no filler episodes. Each minute was used and none was wasted, which added to the suspense and substance of the story.
Acting: In the parts where the characters feel emotion, the actors portray it very well and their reactions make you feel things. Also, the chemistry between the actors is there. Especially the actor who played Jing Yi; I could tell he enjoyed playing that character and is low-key my favorite character because of his personality.
Music: There are some songs that I would listen to on repeat because the lyrics and the way they sing is expressive and sound good.
TL;DR Despite it being low-cost I think they did pretty well. The wardrobe and makeup were perfect. A fluid story with lots of stuff to piece together and excellent acting that fits each character. The music is expressive, and when they put it in the episodes are appropriate for the scene/context. Since the insurrectionist was someone I didn't expect, I wouldn't mind watching it again to see the little details I missed the first time, though I wouldn't go through that whole rollercoaster again if I wanted to.