Just seen Saw II last evening. I absolutely loved it. While categorized as a horror film this movie and it's predecessor are really thrillers. Oh, they have the required blood and gore necessary to put them into the horror genre, but the twists and turns of the plot line keep you guessing and on the edge of your seat like a Hitchcock thriller.
In this second installment the Jigsaw serial killer is up to his old tricks. He selects another group of people to punish for their weaknesses whose lives are related through the one bad cop who put them all away unjustly.
I won't give this one away, but the end will definitely suprise you.