According to ESRB, this game contains: Blood and Gore, Intense Violence, Strong Language
Parents shouldn't be letting their children near this game. Beyond the near constant spray of body parts, there's plenty of objectionable language and content. Also, you shouldn't be letting them read Warren Ellis' comics either.
FPS Fans: this is it. The first great console FPS to come out on the PS2. Flock to it as quickly as you can.
I'm not sure, but it seems to me like the developers of this game actually had something against Deaf and Hard of Hearing gamers. Not only will the lack of subtitling leave them guessing as to the as to the game's well-written plot, but there is quite a bit of voiceover within the missions, and completing objectives without hearing it can be considerably more difficult.