Ok, so it's no Prey, but it's pretty good. The Doom III engine, however, doesn't really hold up all that well over time because of the unique look of it...the whole thing looks just kind of fake and cheesy now that the 'wow' factor has worn off and better engines are out there.
That said, I downloaded a mod by the name of Parallax Extreme or something like that. Basically it's a combination of a few mods offering better textures, parallax (?) mapping, slightly better lighting and a few other perks. It makes the game look about 5X better and more up to date (for whatever reason it actually takes away from the 'cornyness' of it all), but has a few bugs (have to hold down shift to run, have to reboot the video settings through the console every time you start the game in order to have a higher resolution). All in all though, if you're playing this ever again, try out the mod...pretty impressive.