First of all, i LOVED season1. The characters was all very good, the story progressed very nicely.
However, Season2 just removed pretty much most good characters.

Stella(Stephanie Lee) was a perfect character. She was quirky funny and her English is native speaking.
When she was replaced by sally in Season2 it was a huge downgrade. Not at all the same funny quirky character, she had some funny parts but overall not anywhere near Stella. The worst part was they tried to replace Stella with another "English" speaker but Sallys English is so bad its just annoying.

Also the loss of Cha Soo Ho(Lee Yi Kyung) was huge, he was a perfect fit and he was cemented as the main Police connection in the story. His love interest in Stella was also so fun and made a fun interaction between then two.

In Season2 the main Police connection lead was mild and lacked in most ways.

Kang Dong Sik was the most annoying character in the series, and it was much worse in Season2, over acting and just annoying.

The best part of both seasons is Baek Beom, I love series with someone smart and how they find things others don't etc. And his acting was consistent and good in both seasons.

Here is why i can't recommend this series.
The show has pretty much a main story throughout Season 1+2, and the show ended without anything at all getting solved. It was literally one of the worst endings every in a Kdrama, that is even worse than Vagabond ending.
It was obviously setup for a Season3, that never happened and never will. It's been 5 years now.

I understand the high ratings if they made review after the show came out, but someone that watched the show in 2024 it's way to high given that the show ends without any conclusion at all.

Avoid.