Not a good substitute for a porno even if it's often written and acted like one. Saw is actually one of the more underrated films I've logged on here, with virtually none of the characteristics the franchise has become (in)famous for. Tense and fascinating throughout, with a very interesting pair of villains and restrained use of gore and violence.
Of course there's lots of silliness and holes but that's almost inescapable in horror and in this case only added to my enjoyment. A great thriller, much more in line with Seven than with Hostel.