The only reason I gave it a 8.5 and not lower than that is because I was really enjoying this drama until ep 14 came. I feel like after the time skip, the story became very chaotic and rushed with too much emphasis on the main couple (mi jeong and gu). Chang hee's story was so sudden like, when did he and heon a fall in love and why they separate again, what is this connection between him and that ex bf of hyeon a and so on... Also as the other reviewers wrote, his friendship with mr gu could have been more focussed, as it looked like the friendship was only from Chang hee's side.
The character I related the most was with yeom gi jeong. I really enjoyed her romance story more than mi jeong's to be honest. I felt like her story should have gotten equal coverage like the other two sibling's stories got.
Overall, for me the story was beautiful until the mother's death after which it went downhill (of course you would want to continue watching it in order to find out what happens at the end). But I would still recommend you all to watch it.