I am a relative newbie to Korean drama and continually being delighted with the gems I find. Utterly different in style and content to Western ones and superior in many respects. This series takes AGES to get going, mostly because the female lead's character is practically non-existent and thus boring to watch, until you understand why she is the way she is, a meek woman cowed by years of emotional abuse and betrayal by a bully of a husband. She develops brilliantly as she escapes his clutches to become an independant woman. Lee Dong Wook is outstanding as an emotionally scarred man with a horrible past he can't escape. First a rotten childhood and then he ends up being the sidekick to a vicious chaebol heir who treats him as his personal slave and worse. He plays everyone from lad-about-town, psychopath, crazed lover to tortured soul and I found him utterly believable.
The end is harrowing. I am not giving a spoiler, its in the synopsis and its the first five minutes of episode 1. Despite finally having something to live for, he can't overcome the cruelty he suffered in the past and his complicity in some of it. Or his destructive and unhealthy relationship with the heir. Few western dramas would end the way this one did, they wouldn't be brave enough.
Don't watch it for fun because theres not much of that.
I still thinking of this long after watching it. Powerful.