First of all I have to admit that I usually don't watch anything related to the genres thriller/mystery/horror because I get frighted pretty easily but somehow I ended up watching this show.
And let me tell you one thing, it was absolutely worth it (I finished this drama within two days).

And to be honest: yes it can get frightening but in my opinion it was okay, I mean it could have gotten worse.

From the beginning on I really liked how those three lead characters harmonised with each other.
I especially appreciated the way the story develops within the drama, you'll get to know more and more details and after having watched it til the end, I can at least say that much:
When you think that it can't get worse, it will - when its too easy, something is off ...

Ohhhh and the ending ....

So in my opinion you should certainly consider giving it a try, it'll be worth it :))