According to ESRB, this game contains: Blood and Gore, Intense Violence
Parents should be advised that Doom 3 is rated "M" and as such is in no way appropriate for children. It is very bloody, scary, and contains some profanity. It also contains faux-religious images, including a rather elaborate recreation of Hell, which may be too intense for young gamers. With respect to the 9.5 score, which is a very high score reserved for only the best games, I should note two things. First, I am primarily concerned with the single player game, and that is where Jon Carmack and his team were clearly focused.
If you are a multiplayer fan, then adjust the score downward accordingly. The hastily tacked-on multiplayer aspect is mostly average, save for the cooperative campaign. Second, I'm an avid fan of the genre. Doom 3 contains all the conventions that fans like me love about shooters, and that turn off many others.
This is a game specifically for first-person shooter fans, not for those looking for a genre-shattering innovation. For longtime fans of the series, there is a special edition of the game available that contains the original Doom and Doom 2 packaged with the game.
Deaf and Hard of Hearing gamers will miss out on a substantial degree of audio cues, as well as miss out entirely on audio logs, which often give codes for stashed ammunition and supplies. Additionally, the weapon that is essential for defeating the final boss explains itself by speaking for a couple minutes after it is found. Although with a cheat sheet it's possible to play through the game fully, audio is integral to both much of the information in the game and to the design of the gameplay.