I didn't think much of it. The first half is pretty slow, and doesn't have the same gradual sink into unease that, eg, Hostel has. The second half was spoiled for me because I thought the victim's actions were too stupid. For that matter, it seemed wrong that with all the remote places in Australia to choose from, the killer would bring his victims to a place next to a busy road. It's a while since I saw it, but as I recall one victim is able to flag down a passing car (which gives the killer the problem of dealing with someone who will be missed, which goes against his whole creed of picking on hikers) , and another actually escapes that way. In a more remote location that would have been impossible. It's all stupid, stupid, stupid.
The gore is just gore. So in summary, the basic idea is good and the "head on a stick" scene is stand-out, but the rest of it is nothing special at all.