Very intense, very fast paced. For those of you who grow tired of the slow plodding pace of Halo or Call of Duty, Unreal is perfect. It removes reloading and cuts respawn times in half, so you're in the action as much as possible. 2004 was an excellent edition in the Unreal saga with a ton of weapons, game modes, characters and vehicles. On top of that, online plays opens the door for tons of mods and user made vehicles and weapons. For $10, you can't do much better.
PS - for those of you looking for a challenge, playing through the game on God-like is impossible for human beings, I swear...