Story (6.0):
There never seems to be a lack of action in the story, as in it doesn't get boring, but when you try to think about what happened it's a bit hilarious and lacking in true content. A comedic action storyline. You're not going to take the boss fights seriously, it's all there to lead the semi romance. Even failed first loves are shown with hilarity and not taken seriously. You honestly can't take any of this story seriously though there's nothing inherently comedic about it... :P
Don't come here for something to think on, just for something to laugh through. And as a plus, Gong Yoo is in this film.

Acting/Cast (9.0):
Kim Ha Neul did a great job with this part and it fit her pretty well. That said, neither her nor Kwon Sang Woo look the age their supposed to be acting (more so with Kwon Sang Woo), but it doesn't seriously detract from the story. I think they were only like 4 or 5 years older at the time anyway. No overly terrible acting (that didn't fit the story).

Oh I'm going to add another category

Gong Yoo (10.0):
Gong Yoo was in it.

Music (7.0):
Lol, the music fit the comedic tone fine especially in the gangster fight scenes. Did you know Gong Yoo is in this film? The music really fit with him too.

Rewatch Value (7.0):
It's probably not a film I'll come back to watch again but I'm not dead set against it either. By the way Gong Yoo is in this film.

Overall (7.5):
If you're bored or lazy or want to get over a long day at work, don't hesitate to watch this. It's fun and not annoying like I've found some films of this early 2000s era (yes I'm looking at you My Sassy Girl) though it's also not the best of the era. For instance, I'd recommend She's On Duty more than this and bonus it also has Gong Yoo in it.
Also, Gong Yoo is in this film so that's a plus. I can't get enough of him playing the high school student. Did I mention... never mind ;)