Before I start, i would say, I m quite impartial when it comes to reviewing but here i can't help but mention a name who quite literally stole the show for me Noh Min Woo.
OMG!! Keeping aside the fact that he is drop dead gorgeous, he played the most complicated character embroiled in his trauma, suffering and troubled. He has a wonderfully strong Screen presence. He was magnetic.
Sorry for that babble but can't help it, it has been a while since i saw such a great acting. Aside from that this thriller is without a doubt a roller coaster journey with many twists and turns and almost unsolvable mystery and horribly corrupted officials (portrayal of real world) and twisted murderers.

Story:
There is just one word that describes it : Awesome

Cast:
I have already said enough about No Min Woo, who played the beautiful, traumatized, troubled doctor suffering from DID.
Baek Boam is same as first season; rude, uncaring, a bit of a rule breaker, tenacious and most of all Extraordinarily gifted. Though, I wish they don't portray him so immersed in autopsy all the time, it gives off the feeling that he is autopsy maniac. I liked that at the end, seeing Do ji Han's broken state over his friend made him melt a bit (maybe reminded of his lose of frd), also him taking initiative to help him. I wish they would sometimes portray that soft side of his.
Eun Seol: She has to be probably the only reason i m a bit disappointed with the series as her role was pretty much cut short to the point she was a support. Otherwise she was just like last season chirpy, stubborn, smart and headstrong but here her growth as prosecutor is Visible
Do Jin Han: He was given a lot of screen time and he didn't disappoint at all. He brilliantly potrayed the upright, strong and determined prosecutor we all look up to
Sally: Though, m still very enamoured by Stella of previous season, but I really liked her acting. I just wish they didn't give her the same quirk as Stella.
Yang: As the loyal right hand man of Do Ji han, I was very taken in by his personality. He is impulsive, hot headed, impatient and sometimes rude but he is a very loyal, determined and strong assistant prosecutor. His devotion to his friend and immediate superior, Do Ji Han, is very heart touching. I loved their bromance. It was another thing that made the series so engaging.
Chief Prosecutor Gal Cheon, Prosecutor General Noh, Oh Man Sang: As villain, they potrayed the character very well. I despised them to the moon and back which shows the extent of their good acting
NFS staff: whether it is chief medical examiner Ma, or director Park or Han Soon Yeon, or our beloved chubby doctor, they played their part excellently
Seoul Eastern district Office staff: Chief officer Kang Donshik, Det. Moon, officer Cheon Mi Ho, det. Kang everyone had a role to play and they did a great job

Music
I was pleseantly surprised by the music which brilliantly showcased the dark thrilling theme and the OST (Dr. K by MINUE) that kept playing on the appearance of Doc K was so apt with him and went extremely well with the doctor's dark persona!!

I highly recommend it. This is one mystery thriller everyone should watch. It has every quality to be one of the best thriller drama ever. N esp with Min Woo's Brilliant acting, I give it 10/10

PS: Last but not the least, Special mention to Director and story writer who made this series so intense and thrilling. Gomabsenida!!