The acting in Saw is very convincing.  Danny Glover plays an obsessive detective very well while Cary Elwes plays the part of an uncaring doctor driven to the verge of insanity to defend his family perfectly.  This sort of role is the complete opposite of another role he played years before, in Jim Carrey’s hit Liar Liar.  The emotions conveyed on screen, whether it be the obsessive fervor or the insane madness, are so real and powerful that the viewer is left deeply disturbed by the end of the movie.  The lighting in Saw is one of the major contributors to the overall mood of the movie.  Darkness and shadows are dominant and when light is used, it’s almost always harsh and bright.  The white walls of the bathroom emphasize the paleness of Adam and Dr. Gordon’s faces as they realize the situation they are in, while the darkness and shadows of the car garage and Adam’s apartment add to the tension and anticipation of something horrible about to happen.  The flashbacks to past events, including the interrogation of Dr. Gordon, the initial introduction to John (aka Jigsaw) in the hospital bed, the previous “games”, Amanda’s ordeal, and the kidnappings of Adam and Dr. Gordon are placed perfectly in the film and give great background for the current predicament of Adam and Dr. Gordon, and also for the rest of the films in general. 
Two very distinct sounds are found throughout this movie and the series as a whole: the creepy laughter of the Jigsaw doll and the theme song, “Hello Zepp”.  The laugh adds an extra creepy factor to the already creepy doll while the theme song is done so well that it heightens the suspense and shock when the movies twists are revealed and the ending is at hand.
As said before, this movie better fits the psychological thriller category more so than the horror category.  Horror movies are supposed to cause fear in both the characters on screen and the audience members viewing the film.  Saw is not a scary movie, unless you consider gratuitous amounts of blood and gore to be scary.  The scenes that are supposed to make you jump are set up in such a way that it’s very obvious what’s about to happen.  The entire movie is one giant mind game for the characters and the audience.  For the characters, their lives are actually at stake, but so is their sanity and their thoughts on the value of life.  For the audience, the twisted moral of the movie is so overpowering throughout that if you can get past the blood, you’ll leave the film highly disturbed for all the right reasons.  Jigsaw has a reason for putting people in the “games”, and while this reason is developed much more throughout the series, it’s enough to know in this movie that he’s giving people a second chance at determining how valuable they consider their lives.  Ironically enough, Jigsaw himself is not an actual murderer, but instead sets up “games” that kill the person for him.  The sole survivor of one of his traps, Amanda, goes so far as to say that the twisted man actually helped her change her life from the path she had been on.  
