I understand that a lot of people dropped/disliked and rated down this show due to [spoiler]. But I for one have to say that I'm very very glad I didn't stop watching then because every single minute of the show blew my mind.

Contrary to what the ratings might tell you, I actually felt that season 2 was superior to season 1 in terms of everything, cases, plot, new characters that were extremely fun and old characters that continued to be extremely fun. The leads did a fabulous job, and so did all the supporting characters. Admittedly the main antagonist was the typical psycho type that seems to be rather common in KDrama, but even their interactions with other characters was interesting to watch, and the final showdown was well done regardless so I couldn't even feel disappointed about it. But still, I'm someone who enjoys it more when the villain is well written, not just in IQ (which is true in this case) but also in EQ (which is unfortunately not true in this case), which is something impossible to do when it's a psychotic thrill seeker with no real motive for doing all the horrible things that they do, which is why I'm rating the plot slightly down. (The only show with a psychopath that I liked for the bad guy despite being a psycho is Hello Monster, which managed to pull off the psycho character quite well.)

(All that said and done though, I still teared up in the last episode's ending credit's last shot when they showed [spoiler]. So forgive me for ducking rewatch value as well.)