True story or not (and I'm sure plenty of the facts are manipulated) There is nothing in Prey that we have not seen before. Its generic formula and a certain lack of credibility/scientific accuracy certainly do some damage but they don't make the movie unwatchable.
It certainly could have been worse. For a start, it places a certain value on character, something that many b-movies care little for. There is no obvious reason why we should be rooting against the Newman family, who get screwed while on an African safari.. Their guide is attacked and killed by a lion while escorting the youngest Newman on a pee break. The hapless family is forced to hide and wait in the lousy little tour jeep, until Mr. Newman shows up (he's working construction on a local dam) Meanwhile, three hungry lions are waiting patiently outside.
So the film doesn't have us disregarding the protagonists, that's a start. another advantage is the lions being real. There is no five cent CGI in this picture to distract us. Well, some of the blood is clearly digital, but most of it is make up. The movie does have it's share of gore, yet nothing too unrealistic or severely overdone. Prey is shot in a heavily saturated colour scheme and because blood is the only red in the film, it really stands out. (although it is certainly not the only film to try this). The acting quality is nothing to be proud of, but it suspends disbelief enough. As long as it doesn't sound like the characters are reading off a teleprompter, I'm fine with that.
So where then does the movie go wrong, well in the same way that many of these films have, it has been done before. Prey is one in a million, and the only possible distinction for one to see is its protagonists being a lion, not a common creature feature creature. If lions sound interesting, my recommendation would be the Ghost in the Darkness.
