Well for a start this movie is underrated. I don't think that an average rating of 5.4 justifies how good this movie really is.
This is the first movie that i have ever seen that uses comedy, romance, and martial arts to such a good effect in a movie. Sure, there are other Jackie Chan films with hints of romance, and there is always lots of fun and excitement, but this movie is different, because unlike a lot of his other movies, this one is based on a romantic story, yet still has a lot of great martial arts and some laughs to offer its audience.
What makes this such a great movie for me is that the choreography for the fighting I thought was excellent. The romantic storyline is simple yet effective. It is an easy movie to to watch and enjoy.
Now the rating.... a lot of people probably thought this was going to be an action packed movie. Now there is quite a lot of action considering this movie was intended to be a romance/comedy. It just proves that Jackie Chan can pull off a romantic comedy really well.