Started out great, plunged at the end (WARNING: Spoilers)

Rating: Null/10 (14 November 2004)

Two men, Lawrence and Adam, a physician and a photographer respectively, awake to find themselves chained to the opposite ends of an abandoned restroom. Between them, out of reach, is a dead body, and scattered about the room are clues as to their abductor's identity; the doctor (played by Cary Elwes) figures out that it must be the "Jigsaw Killer", who places his victims in traps where they must kill or risk death in order to escape. The woman from the movie's publicity posters is the best example of this: her head has been placed in a "reverse bear trap" that will crash through her skull unless she can cut the key out from another victim's stomach in time.
I got the same feeling watching Saw as I did watching Jeepers Creepers. Started out great, and fifteen minutes into it, I thought I was watching the Next Great Horror Movie. Then the whole thing plummeted rapidly and never got turned around again. Admittedly, Saw started its decline later than Jeepers Creepers did. For most of the movie I felt the rising tension that a horror movie is supposed to evoke. But when the story neared its conclusion and we see how it all got started, I couldn't see how this movie got off the ground without a major re-write. The following is a list of spoilers, so if you still want to see it, read no further. But in order to explain why the movie was such a disappointment, spoilers are necessary.
SPOILER 1: The villain "Jigsaw" is really a cancer patient--yes, a CANCER PATIENT--who looks like he's been on chemo for about six months. And he's supposed to be able to overpower everyone in the movie, including a much younger and fitter Adam (Leigh Wannell). Huh? If someone looked as bad as he did in his early hospital bed scene, I can't imagine him getting up and walking without assistance, but here he is enacting his evil schemes on people who should be able to beat him up with one arm tied behind their backs.
SPOILER 2: "Jigsaw" is also the 'corpse' in the middle of the room, lying between the two men. He plays dead. For seven hours. Next to a medical doctor who has examined him before, for heaven's sake. It strains credulity that the ruse could go on for that long, no matter how panicked Elwes is supposed to be. In seven hours he never notices the man breathing or moving, even when Jigsaw responds to his actions. (At one point, Adam gets electroshocked to see if he is faking his own death.) And Adam at first doesn't seem to recognize the doctor, even though we later find out he has been tailing him and photographing him for some time. If they were blindfolded, it would make sense. They aren't, and it doesn't.
SPOILER 3: The plot hinges on too many people doing too many stupid things. Wannell's character thinks there's someone in his apartment; he doesn't get out and call the police or anything, but tries some ripped-off-from-Rear-Window trick with his photo flash. Well, in Rear Window, Jimmy Stewart only tried that trick because he was a paraplegic and had no other options; in this movie it's just plain dumb. And the cops don't act like cops, they act like Nancy Drew and let the villain get away, getting one of themselves killed in the process and the other (played by Danny Glover, who must have some blackmail photos hanging over him to be in this movie) seriously injured.
All in all a great, horrific premise that got mangled because Wan and Wannell (who wrote and co-starred) wanted a 'dark' and surprising ending, but couldn't or wouldn't think up an ending that lived up to the initial premise.