I should start by saying this is actually the 2nd time I'm watching this drama, and although it's now among only a handful of other dramas I've loved enough to Re-Watch, my first watch wasn't all that enjoyable for me, and after completing it my final rating was a mere 5.5/10. Truthfully I don't think I was mature enough several years ago when I first checked out this drama, since it deals with a rather heavy subject matter (Cancer) and I was only a teenager at the time. Now as an adult I can safely say that although it's been slightly less than a decade since this drama came out it's truly one of the most beautiful and touching stories I've watched from Korea.
The story had amazing flow throughout. I tend to watch dramas on increased speed if it starts to feel slow, but not once did I speed it up at all! The love-story between the ML and FL made sense, you could feel the fact that these characters were falling for each other. Outside of the main leads all other characters didn't magically change to fit the story, everything felt right and natural.
The acting was spot on Lee Dong Wook is a KDrama actor that I truly admire, and his work in this drama was no different, my first time watching this I felt that the FL was too whiny, but now I felt that EVERY SINGLE TIME she got emotional it was heartfelt she TRULY transformed into her character. All other actors did phenomenal in their roles as well, there wasn't a single weak link in the cast!
I typically don't pay attention to music in dramas, but once again this drama blew me away with it's perfect ballads and songs that were meaningful, yet also pleasant to listen to.
Rewatch Value is a 10/10 for me, because I literally just Re-Watched it, coming from someone that has over 100 dramas/movies in her "Plan to Watch" list that's pretty darn special!
All in all this drama was a delight to watch, just keep in mind that it's pretty heavy so go into it prepared to shed some tears. :)