Want back my invested time. First of all this film is well made in certain categories such as: Cinematography, Editing, Acting and even has realism that is easy to believe can really happen. I truly wanted to like this movie but I was forced not to.
I've watched 1000's upon 1000's of films in my lifetime and am a big fan of Horror/Thriller films. I don't mind movies where the antagonist(s) "wins" in the end. Take "The Devil's Rejects" as an example of a film where this premise works. I watched "Wolf Creek" and it has the same feeling as "Eden Lake" where they emotionally invest you in the main characters and you feel like you went through what they went through only to see all hope dashed and evil win.
To me that is a waste of time. Make a person care and then p*ss them off in the end. A person should get some kind of pay-off when they watch a film and if that pay-off is straight out anger towards the film itself then nothing can save the good graces that the film already established.
I'm not saying that depressing, bleak, dismal endings don't work because they certainly do. I am saying that I want to be somewhat rewarded for sitting through a movie. If I don't feel anything but base anger (which is rare) I can't recommend the time spent watching.