Some of the best AI i've seen in a game....
Graphics: Absolutely no slowness in this game, and the graphics great enough to let me identify what i'm holding, or who i'm shooting at.
Sound: Reminds me of Unreal, and the voices are really killer...literally. The music is great and the weapon sounds are great also
Gameplay: Quake 3's gameplay is very well done, the AI is very tough your really notice the difference when you pump up the level (which i would not recommend for new players).
Quake 3 is very well done game overall, and is one hell of a classic game.