I guess the movie deserves the "torture" tag, but for all the wrong reasons. The German distributor made this sound enticing, because they added "Martyrs" on the cover. I don't know what they were thinking, but Martyrs is more than gore and effects. Some people might like it for only those things (I don't count myself to that group), but you can see that the filmmaker was trying to say something there.
Back to this one, where the main actress is not the main problem. For those of us who didn't know it, she is (was?) in the adult film industry. While I wouldn't say she's a great actress, I thought the performance was at least slightly better than the one given by Sasha Grey in "Smash Cut". I didn't watch the Girlfriend Experience, but I still wonder where all that hype came from.
The acting overall is not really good, but it's the story structure that really puts this movie to rest. And don't get me started on the anti-climactic ending. This makes "I spit on your grave" look like the Citizen Kane of that "particular genre". And that's not a compliment for either of those movies ...