Things overstay their welcome.
The first entry in this series came in as just "OK" in my book, with the second falling shorter. The third time is definitely not the charm. There's about four different parts to this one, and only one of the four was really remotely interesting. First, we have a long setup section where the fate of Dina Myers' detective comes about - and then is promptly ignored. Then we get two more threads - one where a father is forced to choose to save or sacrifice people involved in the hit-and-run death of his son, and one where a doctor is forced to keep Jigsaw alive long enough to see the result of the father's game. Only, the father didn't really have a choice, did he? He always had to try to save the victim, because otherwise he wouldn't be allowed to proceed himself - he could be completely greedy and still "win".
And frankly, Jigsaw's game made no sense. How could he possibly know how many people would survive until the end? If Jeff did save everyone, there could have been four people showing up. How would he know what would happen then?
The doctor's story was only marginally better, but that mostly concentrated on Jigsaw's assistant getting jealous at the attention paid to the doctor by Jigsaw. Also a fairly inane storyline, as a Jigsaw - Amanda love triangle is not really what I wanted to see.
The fourth thread was the shortest, but also the most interesting, as we saw flashbacks to how the first movie was set up from behind the scenes. That actually had some interest, but only in the context of the first film - it didn't really add anything for me to the current film.
As for the traps, they got more elaborate, but also less interesting. Not sure why drowning a man in pig carcasses would be a fitting death for a judge, but there you are.
So all in all, a pretty disappointing and tedious entry in the series. Two very middling stars.