Well if you are looking for a good investigation drama with nice acting and happy ending then this drama is for you.

Good sides : Good acting, Good investigation, Good story telling (only criminals),
Happy ending,

Bad sides : No romance, Too much happy starting and ending, Less criminals story,
Less thrilling. No mystery at all.

In the end, I suggest if you are looking for a good (not best) detective drama for time passing then you can watch. But this drama isn't mystery or thrilling, just a good investigation.

Moreover, there are many better dramas than this. Like : Mouse, Love me if you dare, Vincenzo, Vagabond, Signal, Flower of evil, Healer etc. (All I watched)