I have not purchased that movie yet, but I am wondering what player you have? Do you have the Samsung or Panasonic? I actually was plan on owning all three on Bluray after I purchase the Panasonic player.
Yeah, there's a lot of grain, especially during the darker scenes with Lawrence and Adam in the room. I would think it's intentional, because it seems like "Saw" looked kind of grimy or dirty even in theaters.
I think it pretty much replicates the source material pretty well, and some shots actually look very good to my eyes.
I actually think it's one of the stronger Blu-ray titles. I love the look of this film. It's got a gritty look, but the grain doesn't interfere with detail - in contrast to Pearl Harbor where excessive grain mars detail.