I could always sympathize with John Kramer(jigsaw) on some level because i watched my mother die from cancer. he has easily become my favorite character in the genre. seeing this installment just shows even more, the man was a genius. twisted as he may have been.
this movie focuses on the events in the aftermath of Saw III and Jigsaw's past. We see more of what drove him to the point he was at, and we get to see his first game.
the main storyline is about Detective Riggs trying to find Detective Matthews from Saw II. its now been 6 months since his disappearance. i dont want to give anymore info away, b/c realization is half the fun with this series. ill just say it goes back and forth between Riggs situation and looks into Jigsaw's past.
The overall story is by far the most interesting in my opinion, even if only for the better look into John's past. not that the rest of the movie falls short, this is possibly the most engaging in the series. the traps are very clever, and in a case or two the pons really seem to deserve their fates.
i dont know how they'll keep the series going after this entry. Tobin Bell(Jigsaw) is the face of this series and a future horror icon. excellent movie.