I know villains are meant to be hated but I can't help trying to find any good qualities on Min Ho each episode (It's Kijoon :)). He acts like a psycho, of course, but I think his father is the one whom made him like this. His "good" brother certainly did not help either.
In my opinion, his love for Yeon Hee and his son is undeniable. When he's with them is happy. Perhaps that's what he always wanted to have.  His life would have been so different if they had married...
I can't justify his crazy behavior but his life has been so hard and I can understand him a little. He's a patetic character, like Um Ki Joon said. I feel pity for him.
What do you think about him?

He is not bad
he killed his twin brother
forced his brothers wife to live with him. Plays dad for his brother son that he killed.
locked someone up and framed that person for a murder he did.
kidnapped the prosecutors daughter.
keeps beating his lackey
bribes officials.
instigated other murders.
killed a girl at the begining of the drama.

yeah his dad is abusive but that doesnt justify murder
if any kid gets spanked and grows up to kill people then 90% of the world will be in jail.
I don't say he isn't bad. His behaviour isn't justificable. I only was speaking about his love for Yeon Hee and his son, not his brother son, HIS SON. I think that's clear since episode 1.
I get what you are saying.
I feel Ki joon did an amazing job in portraying Min ho! I enjoy how 3D he is as a character. He is not just the bad guy who does bad thing. He is the complete psycho that does crazy and frighteningly bad things. However, he is the guy who is insanely jealous of his brother, who seek his father attention and who truly loves his woman and his son. That's why his psycho side is even more scary because without that part of his personality, he is uncomfortably normal. I really want to applaud the complexity of this character and the wonderful acting. 
From my point of view, i think psycho in real life must be like Min Ho. If you cross their path during their everyday routine they must seems like normal loving husband or normal loving father. But, when you don't see them, they do the most horrible and frightening thing in the world.
For me, the father really gives me the creeps. He is like a more calm and inhumane version of Min Ho. I can only imagine all the horrible thing he must have done for his beloved company.
However, I don't pity Min Ho but I don't hate him as much as I should knowing all the horrible thing he did. I just feel that it is unfortunate that he chose such a path in life.
Also, I really hope Min Ho get properly punished. I want him to reach the bottom. I also hope that one day he will realize how bad what he did was but at the same time I feel that his insanity has reached a level where he can no longer turn back.
I really hope the father will lose his "beloved company". I think that will be the most severe punishment for him.
In the Ho family, the one I truly pity is the little boy. I can't help but wonder what kind of person he is going to turn into with a family like that.
You have explained it great. I think the same as you.
Um Ki Joon is doing an incredible work as Min Ho. He's able to performance two different sides of the personality of Min Ho. On the one hand, the psycho who kills Ji Soo, Seon Ho or Jennifer. We obviously hate him in these scenes. He acts crazy and scary. We can't forgive him.
But on the other hand, he's a loving father for his son and we can see that his love for Yeon Hee is still alive. He was so touched when she took his hand and he felt so bad when he noticed that Yeon Hee had listened to Jennifer's murder. I can't hate him in these moments.

It's obvious that he will be properly punished and I think that his best punishment will be that his falldown comes from Yeon Hee. She's his weak point.

Min Ho's father is truly scary. He has manipulated his two sons for his company. Now is going to make that Min Ho takes the fall for the tax evasion because he needs someone to take the blame for it. Min Ho has never felt loved by his father but now he's going to hate him even more. His reaction is going to be terrible.
And yes, poor little boy. What a family he has! :(