I think the drama as a whole is a great experience, I acknowledge that slow dramas can be hard to watch, and this is on the slower side. The beginning is really intense and intriguing. The story goes back and forth from the current state of the investigation to the flashbacks from potential suspects. The length of this drama is thankfully on the shorter side, for Chinese dramas.
>Acting ---is pretty good<
I have no complaints, there are many actors and they did a great job. There are a lot of moving pieces in the story, so I wish you luck when keeping things straight.

>Story--the actual mystery was interesting, but I might have changed the way it was told<
The actual mystery and story behind it was fun to unravel with the detectives, they aren't dumb detective thank god. But the fact that we have to keep switching from one setting to another can be confusing if not annoying. There were definitely several episodes in which there were just endless flashbacks, which I felt diluted the mystery further, but I promise some of the flashbacks are pretty interesting, so pay attention. The story can drag at points, so persevere!
Side Note: I don't know why they added the side story about the detectives themselves, but I don't think it added to the plot, I think it detracted from it

>Ending--most good thrillers leave the answers to the last episode but...<
Unfortunately, they did not leave the final answer to the last episode, and the last episode ended up being a little too long, which detracted from my rating.