This movie is really stupid, in a way as if a teenager wrote it. I wouldn't even know where to begin listing all the issues and implausibilities with the plot as well as the characters. In short, if you're expecting a serious "Crime - Mystery - Thriller" like it says in the description here, you'll be a bit disappointed. The movie is a weird mix of cheesy high school romance elements and a rather shallow and unconvincing serial killer story, accompanied with some amateurish acting and at times quite cheap sounding music. It doesn't help that visually it looks a bit "low budget" too.
Having said all that, the movie does have its charm and is not boring. It also gets a little bit more interesting towards the end. So if you can ignore all the problems and don't expect a masterpiece, you'll be entertained.