This is going to be a short review but one word that may encourage you to watch this drama is 'mind-blowing'.

At first i wasn't even sure if i was going to like it even if it got great reviews from others but now i can totally relate to the other viewers as well. The way the drama deals with mental issues is great. This makes me realize that even if someone looks normal on the outside, it doesn't mean that s/he is normal inside as well. Some people don't even know what are mental illness and they are mostly called a 'name' for having those issues. Those suffering from it even get depressed as people can't understand them or they are pushed to a corner.
So this drama is a way to make us realize that.