For what it is,it does its job of entertaining.
But it's more a thriller than horror. I wasn't particularly scared at all. But pacing and tthe simple plot with the setting is somewhat fresh. The actors did a good job. I mean, I don't know if people 45 thousand years ago were that skilled in communicating and language. Like did they have the concept of North and South back then?
But overall I enjoyed the movie. If you are looking for something more than stone age people fighting for their lives against unseen enemy then this won't be for you, as that is basically what it is.