My theory, based on doctors I have known: medical students spend so much time in school and internships that they miss normal adult social interactions, and consequently suffer from arrested emotional development. I submit "Doctor Slump" as a case study. The maturity of the main characters wasn't what one would expect of people their age.

This series suffers from trying to be too many things: drama, romance, and comedy; the first two worked well, if inconsistently, but the third came off as juvenile and misplaced. Whether the attempted comedy was a script choice or a directing choice, it was so off pitch and over-acted that it made me want to throw things at my TV, and is primarily why I didn't rate the show higher.

A couple of things I found baffling:
1) Ha Neul's wardrobe seemed chosen to have her fade into the wallpaper - neutral on neutral. For a while I thought it was a visual reflection of the character and would perk up as her personality evolved, but nope, stayed boring and unflattering throughout.
2) How did these characters last 16 episodes without dying of cirrhosis? I'm honestly worried about the health of the script writer if she thinks this level of consumption is normal or healthy.

On the pro side: based on my personal experience, the script's treatment of depression, it's manifestations, effects, and recovery hit all the right notes, particularly in presenting Ha Neul's unresolved anger from the violence and mistreatment at work as manifesting as helplessness, defeat, and demoralization. The development of her character and behavioral responses during treatment was also realistic and well handled. The development and clarity of Yeo Jeong Woo's character was a little more murky to me, but I did like that solving his business problem didn't magically solve his personal problems.

In contrast to other viewers, I thought the story was sluggish in the beginning but really picked up in the last eight episodes. The plot lines and character arcs set up in the first half of the series began playing out and resolving and that was a lot more satisfying for me than the build up. I also liked that we finally got to see a more holistic picture of Nam Ha Neul after eight episodes of more than I ever wanted to know about Yeo Jeong Woo.

I loved the gradual reveal of the family dynamics and IMO the characters were perfectly cast. Park Shin Hye is compelling in everything she does, Jang Hye Jin was the perfect Mom for this story, Yoon Sang Hyeon really grew on me as the series progressed, and I want Hyun Bong Sik's Tae Seon as my real life uncle and Kong Seong Ha's Lee Hong Ran as my real life best friend.

I won't rewatch it, but I mostly enjoyed it the first time around.