Legendary.
This game looks beautiful, even now - going on 8 years after its release. The levels still look amazing. Some are vibrant and colorful, while others are dank, dark and produce a sense of evil. The characters are clean cut, and easily deciphered from the non-stop fast paced action.
Then there's the sound. This game is never quiet, and sometimes that would be a bad thing, but in this case, its not. Each weapon sounds purposeful, loud and destructive, not like some wimpy ass *pew pew* gun. Everything sounds satisfying and meaty, everything. The soundtrack is amazing, comprised of mostly fast paced techno, it really sets the mood. There are a few mellow tracks in their too, for those space/ancient themed levels.
The gameplay though, is what really makes Unreal Tournament, Unreal Tournament. Pick this up now if you already haven't.