Let's start with what I liked:
The friendship between the four main characters was very special. They were each in a different area of the fashion industry. They'd been friends for years and were totally there for each other. Every time one of them needed something or was having a bad day, the others were there. It was a case of, "I can trash talk my best friends all I want, but if you don't treat them right, I'll cut you!"
Chae Soo Bin as Pyo Ji Eun - I love this actress. She is just precious. However, she spent the entire show running from one emergency to another.
Lee Sung Woon as Joseph - I loved him and the character he played. Kind of a genius with self-esteem problems. I loved his interactions with his assistant as well, she did most of the talking to others when he went inside his shell. They'd worked together for a long time and were supportive of each other.
Park Hee Jung as Ye Seon Ho (supermodel) - cold stare, bad attitude, with a strong sense of justice for herself and others. When she stuck up for the younger models, loved it.
I was SO glad this didn't have more episodes. Each episode that I finished, I was ticking it off in my head, anxious to be finished with it.
Happy ending, though it was very lackluster.

That's it. Now, for the things I didn't care for:
Choi Min Ho as Ji Woo Min. I've seen him in other roles, and he was okay, but as the romantic lead here, he left a lot to be desired. I didn't root for him as the lead, he just didn't have enough presence. He did a lot of staring at the FL - were they supposed to be longing looks? He always dropped everything when she needed something, which she didn't really appreciate.
Script. This was a show with ADHD. Too many characters, most of them not likeable. Characters yelling at one another constantly. Was that supposed to relay the stress of working in the fashion industry? Someone was ALWAYS yelling at someone else. Some funny parts, and then it would turn serious. What did it want to be? What was the purpose of Shim Do Young's storyline? He showed up periodically, borderline creepy, and did nothing to advance the story.
Romance. What romance? We got flashbacks of the couple in their happier days. Why did they break up? She had had boyfriend/boyfriends after their breakup, which might be realistic, but, for me, it lessens the bond between the leads, and here, it made her seem very indecisive. I didn't think these two had ANY chemistry with one another. They were great as friends, but nothing more.

I love seeing good stories about friendships, and I did like that aspect of this show, but not much more than that.