I'll start with what's more obvious for me, they're very incompetent for those who are praised to be the best detectives. The mystery solving part of the drama was very lacking and that's what annoyed me the most.

A lot in this drama lacks conviction and commitment. Deciding to trust someone just because they're supposed to be your friend but had hidden important information from you doesn't seem very sensible for someone in the middle of an investigation. Even when things are blown out of proportion like FL's expulsion, the train of thought associated with everything around it doesn't make much sense.

I couldn’t finish it all, I just watched the last episode. The ending also lacks conviction. It feels like lukewarm water when you're trying to take a shower on a winter day. It's not satisfying