Well, concerning the visuals, there is a way to make them look a bit nicer, look here:
Deus Ex on modern systems [http://kentie.net/article/dxguide/index.htm]
This is a handy guide that explains in detail how to use a new, better render engine with Deus Ex and replace some of the textures with high-res versions. It is not entirely trivial to set up (although I think it is still relatively easy to do), but it gives you some really nice modern-day features like widescreen modes, anti aliasing and anisotropic filtering and advanced DX10 lighting and also fixes some issues which come up while running Deus Ex on modern systems.
It obviously still looks dated, but I think those enhancements should make it much more enjoyable on modern systems.
For the rest, well I still have a special place in my gamer heart for Deus Ex, because (as others have said thousands of times before me), it gives you an enormous amount of freedom how you can play the game, has a compelling, well written story and an incredible, detailed background, especially since it has that dystopian, cyperpunk-ish feel to it which is pretty rare in games compared to standard Fantasy or Sci-Fi scenarios.
In combination of those factors, this is still a very unique game and there have been games here and there that managed to recreate some of the compelling aspects of Deus Ex, but I think there is still no game who nailed the combination quite as well as Deus Ex did, so I think it is till worth checking out today.
Needless to say, I await Deus Ex: Human Revolution eagerly