I gotta agree, it is the best game ever. Even though I haven't played it for a few weeks due to my Borderlands 2 addiction, I will go back to it any time soon, specially on MonsterHunt.
I've also played the later releases like ut2003, ut2004, and ut3 and they still not feel the same as playing the first game. The most I played ut2004 was for 2 weeks online and completely gave it up permanently. I even tried ut3 but once I beat the single player campaign, I never launched the game again or played it online. No matter what games I play or how many games I play, I still go back to the original UT GOTY (UT99).
I think Epic should make a new public patch for it that includes a new renderer and other features from newer engines. If they would do that for UT99, I would be willing to spend whatever they ask for because I know it will be well worth it.