I wanted to rate this drama 9. 5, but I changed my mind and give 10.
1. Story - In my opinion the story is simple and can be found in other movies or kdramas.
It's possible that also in future to be done other movies which will be similar, because of that I cannot give a bad rating.
2. Acting / actors
Lim Ju Kyung :
- definitely this character is very well build.
- she is the centre of this kdrama, her story and the way it is presented will make the viewers to watch this drama in order to see how she manage to survive.
- I really liked how this character was performed, it felt so real her suffering and her love that definitely I had tears in my eyes watching this drama.

Seo Jun :
- his character make me laugh, cry and wishing for a second sezon.
- he definitely was very well performed and I enjoyed each scene.

Soo Jin :
- I know that her character, it's a turning point of this kdrama and her role is very important.
- unfortunately I could not feel intense emotions as friends (Soo Jin and Lim Ju Kyung) or love (Soo Jin and Su ho) ; I had felt passing thru the screen, a little spark of hate between her and Seo Jun, which really impressed me.

Su Ho:
- I really was impressed, why?
I was aspecting something boring with a neutral face were all the people bound in front of handsome guy, like he don't need to send any emotion, because his good looking face will be enough, in order that the viewers to watch this drama.
- this character was well performed, I really felt his emotions, in his love relationship with Lim Ju Kyung and his friendship with Seo Jun.
-his character make me laugh and cry and wishing a second sezon just to see his reaction and how would he evolve as an adult if Lim Ju Kyung will not be part from his life.

I write above impression about main leads, but I have to say that the entire cast did a great job and I enjoyed every scene.

3. Acting / scenes
- there are some scenes which are missing from school trip (what happened with Seo Jun bracelet, the way back home from trip, how they stayed on bus? )

I think that viewers need to take in consideration that this kdrama needs to respect age category (15 ages or more ), so it's possible that scenario and acting was adapted in order to respect this aspect.

I rate 10, because I saw this days another kdrama, which I enjoyed, was very emotional, had a good story and great acting, but I didn't laugh or cried, as much as, I did on True beauty...