According to ESRB, this game contains: Blood and Gore, Violence
Parents should be aware that the game features large amounts of blood, gore, monsters, and the ever-popular zombie decapitations. Young children will be severely freaked out, and the game's "M" rating is well deserved. There is no sexual content, and only one instance of questionable language at the game's end.
Fans of action or horror should rent the game first. The controls and game design are archaic beyond belief, and anyone who's played the Resident Evil games before may find that Zero is too similar to provide any worthwhile stimulation.
Resident Evil junkies might want to see Zero's disappointing story and appallingly thin connections to Resident Evil play out, but the game's hyped team feature is dull and the item system actually makes it worse than older Resident Evil titles in the series. Mild props do go out to Capcom for making this many Resident Evil games before whipping out the old "giant scorpion" routine, though.
Deaf and Hard of Hearing gamers are basically screwed. None of the game's cutscenes or dramatic dialogue provide text, and there are a large number of significant auditory cues within the game. It's possible to play through since most clues and hints are presented through text, but you'll be missing almost all the story—the game's biggest draw.