Wow, Zombie. That's the worst review that any of the regulars here have gave Martyrs and it's still a good review.
Personally, I didn't really notice how the effects were done at all. I just loved how I was so completely drawn in to the suffering the girl endures and then realising towards the end(as she does) that there will be no salvation for her and her death will be her only way out. I even ended up feeling kind of conflicted at the very end in wishing a quick death for her and also wanting it to last just a little longer as this was the first time a film had really affected me so much.