I know this thread is old but I just saw saw 4 on dvd for the first time
heres my take on the series
The first one was amazing. They came up with an awesome plot for a horror movie. The traps were simple yet amazing. They all played on the "how much are you willing to suffer to live" theme and in turn value your life more since you didn't value it before. These days its hard to make an original movie, especially a low budget one thats not based on any previous book or movie or whatever. So they had to make it gorey to attrack people. But still, it really wasn't that fucked up (compared to the newer ones). You honestly can't rank the original saw as a great movie.
Number two was pretty sick. It took the same theme as the first but did it in a different way. It was almost like a reality TV, big brother (the show) type satire. The traps got a little more fucked up (but still awesome), they had to make it even more violent to appeal to the masses, and the special effects/photography was a little better. The plot of the movie was awesome and the twist was immaculate. this was a great movie.
So number three comes along. They rush to make this movie and it comes out like shit. The plot is weak as fuck, the traps no longer play on the original theme. The traps themselves suck. To make up for everything else, they just add in more and more gore and violence. This movie sucked.
Number four was complete garbage. The plot blew cock. The acting was shitty. The cinematography was awful. The traps were stupid. To make up for all this they just added more and more and more gore and fucked up shit-the brain autopsy is a perfect example (pointless and fucked up). The only parts I liked about the movie were the history of jigsaw and the masuleom trap.