According to ESRB, this game contains: Blood, Violence
Parents probably don't want their small children playing Primal. It features many bloody scenes of violence and death, most of which involve brutal killings on part of the player. Of course, these are commonly committed against demons, monsters, and other non-human creatures, so this may not offend some parents as much as others.
Those who like goth fiction such as The Crow or Buffy might think Primal looks cool, but don't be fooled. Unless you enjoy anything with gargoyles in it, Primal will bore you to tears with its half-baked gameplay, cookie-cutter plot, and limp dialogue.
Fans of series with goth aesthetics like Devil May Cry and Soul Reaver may find the look and feel the Primal's world interesting, but given how much better both those games are it might be difficult to get into something as mediocre as Primal.
Probably the only people who would get their money's worth out of Primal would be graphics fans who delight in nothing more than seeing beautiful environments rendered in the PlayStation 2. This is the one and only area Primal impresses in.