I enjoyed the last couple of episodes more than the rest, though they still somewhat left me dissatisfied.

What I liked:
Acting was excellent. I love Park Bo Young. The only time I don't like her acting is when she cries. It is loud and it's overdone, so it makes me want to laugh. She did better in this drama. She still had a couple of over-the-top moments, but her moments of quiet crying were very touching. Plus, she had the perfect, calming voice for her character's job.
Lee Jeong Eun as Nurse Manager Song. I love this actress. She's got that tough exterior and that inner softness/caring. Plus, she has a great voice.
Noh Jae Won as mental patient Kim Seo Wan. This was a tragically beautiful character, and he did an amazing job. As he struggled between fantasy and reality, there was a wonderful sweetness (or maybe innocence) about him. His relationship with PBY's nurse Da Eun was terrific to watch.
Relationship between Da Eun and longtime friend Yu Chan. I'll admit, in my heart I thought they would be a better match for each other. So supportive of each other, with the fighting that often comes with people that have known one another forever.
-special effects were good. Physical displays of what was going on in the person's mind.

Things that let me down:
Being in the medical profession, I have a difficult time suspending disbelief, especially since this was a medical drama. Where do I begin?
-she transfers to the psych unit because her previous boss told her to? (Unbeknownst to her, her boss was trying to get rid of her.) It takes a special person to work in a psychiatric unit, and she knew NOTHING about psychiatric disorders, not even bipolar disorder, which is something that everyone has at least heard of.
-she doesn't use gloves when giving injections or drawing blood.
-it's a locked psych unit, but the patient rooms each have a refrigerator in them, and the patients are allowed to have pretty much whatever they want in their room. There were multiple people in a room, if a person wanted to hurt themselves or someone else, they have access to pretty much anything.
-You leave with a psych patient to take her to the bank to open a savings account?
-it's a locked unit, but a patient can get to the roof without anyone knowing? Add to that, there are cameras all over the place and no one saw anything.
-I realize it was a short series, but many of the psychiatric disorders were glossed over and oversimplified. The grown woman that has a contentious relationship with her mom, and all it takes for the woman to be healed is for the mom to bring her the correct kind of fruit. She's miraculously cured and gets discharged. Pep talks seemed to "cure" some of the characters.
-PBY character depression. Came as a result of a tragedy, but was definitely more than situational depression, especially since she tried to kill herself. She had been working on the psych ward for some period of time, her case was so severe, and the voice overs showed that she was aware, to a certain degree, that she wasn't behaving right. She didn't seek help.
-I'm sorry, she would not be able to go back to work on a psych unit after having the issues she had. The writers made it seem like she was "cured" as long as she took her medication. Being on a psych unit would be a constant trigger for her.
Then there were the relationships:
-I don't usually have SLS, but she should have ended up with her longtime friend. I was bothered by the fact that the doctor liked her because looking at her made him stop cracking his knuckles, but when they were apart, he went back to cracking his knuckles. She was a panacea for his behavior, that's a lot of pressure for anyone. Yeon Woo Jin as Go Yoon was good, and he's just so cute when he smiles, but I didn't feel their relationship at all.
-2nd couple. She had absolutely no self-esteem, and I could see why after we met the nightmare of a mother. It seemed to me he was always the one doing the work in the relationship. Very unbalanced. Don't even get me started on the fact that she decided to go away for a year. These writers will do anything to include time skips, people leaving, etc.

So, I'm glad I watched it, but was, overall, disappointed. At least I can cross it off my watch list.