According to the ESRB, this game contains: Animated Violence
Parents might not want this game to be available to younger kids since the game's all about hitting people and making them pass out, but older kids should be fine with it as long as fighting games are approved by Mom and Dad. Most of the violence is pretty flashy without actually having any blood or gore. However, as a warning there are a few moves which visibly break bones; two characters have bladed weapons and the bear does maul people -- but that's nothing too far outside the usual realm of fighting games, is it?
Casual PlayStation 2 owners can't go wrong here. It's got a ton of characters, an uncountable number of moves and enough modes to really make the gameplay last for a while. Add in the endings to be unlocked and the bowling mode and you've got yourself a must-buy title.
Street Fighter or Virtua Fighter fans may want to try before they buy since people in either category tend to have fairly strong ideas about what makes a good fighting game. I'm also sure that most people who play fighting games enough to be a fan of any one franchise probably already have an opinion about Tekken. While this is a very high-quality game, there aren't any fundamental differences in the formula to change anyone's mind. Tekken Tag definitely won't please all comers, but those willing to give it a try on its own terms will be satisfied.
Tekken fans, even the casual ones, must go out and buy this game right now. It's the most polished, most fun, most well-put together package that Namco has ever generated for the franchise --period.