How bad is it? It's cheap and burdened by a gimmick.
Should you see it? If "violent and weird" is more important to you than "well-crafted," yes.
The title is slang for a slap, which is about the only violence missing from this film. In the film, five girls in a car have an accident breaking the headlight of another vehicle, then they panic and decide to cross an area known as "the Eyes" (for no reason other than to have a title). They get pursued by a vehicle with one headlight. Eventually, their pursuer starts doing some horrible things to them and it's actually pretty hard to stomach, so it's fairly well done. The entire film is shot by one camera mounted in their car, which creates a sense of claustrophobia, but also nausea with all the swing pans it necessitates. The cast don't do some very obvious things because of the constraint of the camera gimmick. If you have a strong stomach, it's not too bad.