First of all: I am deeply in love with this show
it's funny, cute, mysterious, interessting and heartwarming.
I feel comfort warching this. It cheers me up.

Plot: The plot may seem easy at first but is very interessting and surprising as time goes on. The characters spend a lot of time discussing and theorizing so it is easy to follow and I felt like i was investigating right along side them, theorizing. The cases are interesting and memorable. I was never bored or skiped any scenes.
Cast: All of the actors portray their character amazingly. The chemestry between them all feels very close and they do act like a group of close friends or family. I am having a great time watching them interact and care for each other. The looks they give each other are hilarious.
Musik: The musik is not outstanding but they underline the scenes perfectly and set the tone. Be it funny, mysterious or emotional.
Rewatch Value: As previously stated, I love this drama. It is my comfort show and I will regulary rewatch it. A big part is the focus on the friendship here.

Overall: This drama is perfect.