I quite liked this drama, and had it stayed on course like it started with the first 2 episodes, my rating would have been much higher.
I liked the focus on mental health issues, especially as it is such an important topic in South Korea for known reasons.
They did well in the start, and I enjoyed the visual creations of different disorders, to make it tangible for people who don't know much about it.

Sadly it also had several flaws in the later episodes. First I have to admit that I was more interested in the side lovestory than the that of the main characters - I really like Chang Ryul, he was brilliant in 'my name' and it such a versatile actor.

The main flaws for me were different ones though:
the drama wanted to show different mental health issues with example stories. One of the first stories was a 43-year-old woman who was so opressed by her highly intrusive and invasive mother that she totally lost it and was in the closed ward of the psychiatry now. Very realistic example so far. But the drama wanted to show solutions veeery simplified. We hear that the woman hates grapes, a food her mother constantly brings her and says she'd always loved gapes. This is the peg for the problematic situation, the woman screams at her mother that she always hated grapes and because of that overboarding behaviour of the mother she 'wasn't even able to order a cup of coffee somewhere herself at the age of 43'.

The drama solves this over 40-year old problem situation with deeply ingrained toxic behaviours with just telling the mother once, so she brings other fruits for her next visit, and soon later mother and daughter happily leave the hospital, like best friends.
Erm, nope, this is not how things are in reality. People don't change like that and longlastig toxic relationship patterns don't change from one day to the other, just because someone says 'bring different fruits.'
The show oversimplified complicated issues that need lots of work (and the willingness of all people involved - that is where most things fail before they even started) and time to get any change, and often even with lots of effort this change never comes. That's reality, the drama wanted to show good endings of most cases, but that's just far from reality obviously.

Same with the ML and his panic attacks. Those are severe too and he had them for many years. Again, it just takes one or two people talking to him with some few friendly words, and yippie, he says 'oh yes, right, I have to address this, I go to the doc, get this treated with meds and my life will be fine.' Again, naaah, if you have severe panic disorder for sucha a long time, you do not just listen to a few friendly words from a friend and then go and solve this. If you have severe anxiety, you are also afraid of things like medication, of doctors who will 'judge' you, of others hearing from your problem etc. It just doesn't work that easy in reality sadly.

Another unrealistic thing was that our main FL, who works as a psychiatric nurse, suddenly has severe depression herself.
Well, that can of course happen, as depression can hit pretty much everyone.
Her depression is major though, so major that she walks in front of a truck to die. She ends up in the closed ward herself and is deep down the depression spiral for a while.

She finally gets out of it and...the older main nurse then begs her to come back and work again in the psychriatic ward. That's of course nice but at least in my country and others I lived in, it would be impossible. If you have a history of attempted suicide and major mental health issues yourself, there would be no way then that you could work again in such position - for your own safety and those of your patients.

Back to the lovestory of the side characters. It was a nice story, wealthy man falls in love with a very poor nurse. The drama left out major issues in Korea, like, what would his wealthy parents say to this choice? We do not get any information about his family, only some few things he says which imply the 'golden spoon' (so does his super spacious and very expensive appartment)

So, after fighting to gain her trust for quite a while, she finally is willing to date him, awkwardly though, but still. He even supports her abandoning her supertoxic 'person who accidentally gave birth to her' (I don't want to call such people mothers) - which is a good idea. But then, things speed up in a totally different direction, obviously trying to make the young woman, now free of her money problems and the toxic mother, a happy, independent person. She quits her nurse job all of a sudden, and wants to become a dancer on a cruise ship and leave the nice guy, who, of course, is also super willing to let her go away for a full year? I didn't find that credible at all. It often happens that K-dramas want to show this kind of 'woman does what she wants'-thing- but rarely have I seen cases where this went believable and smooth instead of doggerel and unrealistic like here.

All in all, it was a good start, it's good K-dramas try to openly focus on mental health issues, but they just don't get it right in the details yet.