Every actor in this series acts over the top. Everything is an absolute drama, even eating pork skin (apparently its a Korean delicacy, pork scratching don't do much for me). But the story lines are addictive as is the main forensic pathologist Dr. Baek Beom. I haven't quite got to season 2 yet but apparently the English speaking head of toxicology is a different person in season 2. The woman in season 1 was ridiculously annoying if stunning to look at.
I will definitely watch season 2 and hopefully the overacting is toned down a little bit. One of the better Korean dramas but not the best.
(edit)
I've now watched season 2 and the overacting is toned down a little. The replacement for the English speaking head of toxicology is just as annoying as the original but not as pretty. The storylines were probably better than season 1 so that's a good thing.
Its just a pity that the two lead characters didn't evolve, they remain the same throughout the two seasons. Baek Beom (pathologist) remains grumpy, and Eun Sol (prosecutor) remains completely useless at her job.
A new character in season 2 is Doctor Jang Chul, now this character has a great storyline and the actor (Min-woo No) does an excellent job. Its a pity its basically all over and done in two episodes. He does carry on throughout the series but the storyline reduces somewhat.
All in all a very good K-drama to while away the time.