I think this is the best of the SAW movies, as it has some surprising revelations in regard to the first two movies and provides more insight to Jigsaw's motivations for doing what he does. First, there's John/Jigsaw who is still dying of cancer-and a woman doctor is forced to keep him alive until the current game is finished--or else she'll die. The explosive device around her neck is connected to Jigsaw's heart rate. Jigsaw's protegee, Amanda (Shawnee Smith), isn't playing the game fairly and is going against everything her mentor has tried to teach her, which causes a lot of conflict. There's also a side story of a man (Angus McFadden of MIRACLES) who wants to get revenge on everyone who was responsible for setting free the driver who killed his son two years before. However, he soon discovers he has second thoughts...
SAW III is a great sequel, putting everything in place and completing the story of Jigsaw, and I hope the ending to the SAW series so that it ends on a good note.