I loved the character development of each character in the show starting from the season 1 upto the 3rd season.I was disappointed with the directors making some characters like Alex. Sometimes I used to feel quite irritating as to what is happening but the directors made it sure I stay glued till the end as to what happens next. Loved the show but didn't expect the ending. Because I didn't expect the ending so I was more impressed by it. I would say everyone did a wonderful job. I loved relationships of ro na-seok hoon, logan-sooryeon and mari-dong pil.It's a beautiful show which properly portrays the current situation of the world well.