Awesome story and amazing acting, there's so little bad things I can write about this drama as it managed to keep me at the edge of my seat and with a box of tissues near me the whole time. That been said, here's my review.

Story
Kill me, heal me is wonderfully written and keeps the mystery and melodrama of the story perfectly balanced with hilarious situations and scenes that will keep you entertained throughout the show. DID is a very controversial illness and there are many discussions about it but this drama manages to depict it perfectly and helps you understand the meaning and story behind each personality. One of the things I really liked about this drama is that it doesn't fall on the typical Kdrama cliché that can become boring or frustrating at times, the story is so rich and heartwrenching that there's no space for that. The storyline is full of suprprises that makes it hard for it to become predictable, even the antagonists have a totally different role throughout the story. The only "flaw" I found in the story  was that in my opinion it lacked some closure to some characters in the end.

Acting/Cast
The acting in general is amazing but overall I have to pay special attention to JiSung's acting. The multifaceted acting and ability to bring to life so many different personalities is amazing. This is the first time I see him in a drama and I have to say I'm definitely watching all this dramas/movies because he's just an amazing actor. The way he changes not only the tone of his voice but also the look in his eyes makes me think he's the best Korean actor I've seen so far!
Hwang Jung Eum's acting didn't convince me in the beginning because I felt it was too similar to her role in She Was Pretty but shortly after, she managed to captivate me as she became a great heroine and developed a heartwarming and funny personality.

Overall, I loved the chemistry between the main characters and how they matured with each episode plus the great bromance that develops between the male characters!!!

Music
Personally, I usually get a bit tired of some of the songs played in dramas. Maybe because I usually watch several episodes in one day and that has something to do with it. But on KMHM the music is amazing and was probably one of the reasons why this show managed to make me shred several tears. The main theme, "Hallucination" is the perfect combination of soft vocals and rap that fits perfectly with the heartwarming and painful experiences of the main characters. It managed to give me the chills every time it was played and even now, after watching the whole drama, I've been listening to it over and over again!

Rewatch Value
I will definitely watch it again!!!!!!

Overall
If you are looking for a different type of story with intrigues, romanticism, mystery and melodrama without falling in the typical Kdrama storyline, Kill Me, Heal Me is everything you are looking for!!!!