First of all, I have not seen the original story, but I am sure the C-Drama is better. It also has a different genre, has more deepening and is more emotional.

The Korean adaption, on the other side, is a short drama with 24 episodes, each around 20 minutes long. It is colorful, cute and lighthearted. One of these dramas where you just can sit back and not be emotionally involved or stressed.
I personally need something like that after an intense drama.

The story:

Shin Sol Yi (So Ju Yeon) is madly in love with her clever and good-looking neighbor and classmate Cha Heon (Kim Yo Han). However, he ignores her caring for him and is rather cold towards her. She still does not give up and clings onto him. When a new student Woo Dae Sung (Yeo Hoe Hyun) joins the class, he immediately shows interest in the sunshine Shin Sol Yi. This is when Cha Hoen realizes he does indeed care for her and the whole drama begins.

In general, the story takes place over a lager timespan. It starts during their school years and shows different stages of these in ca. 17 episodes. Afterwards, the drama moves on quite quickly, showing some episodes at university and how they deal with job until they are something around 30. The pacing was fine, but towards the end everything was a bit rushed.

The characters:
As you can get a small inside from the description above, you notice that Shin Sol Yi and also Woo Dae Sung appear as true sunshines towards the fevers. Even tho Cha Hoen was portrayed as cold-hearted at first, this description soon won't do him justice anymore.

What I really loved were the supporting actors and the friends group. Shin Sol Yi really has some of the best friends you can get in the entire world, and the bond of her classmates was strong as well.

It is been some time since I watched the drama, but there are scenes which I remember still till that day.
Simply, there is not much to say. I enjoyed the drama and will definitely watch it again if I feel down, and so should you :).