I got the game when it was first released, and I played through it on Medium difficulty and loved it. The little tweaks and additions to the engine (like being able to look up and down) were very welcome at the time. The only thing I didn't like about it was the lack of a mid-level save feature...requiring you to complete a level in it's entirety, or start over in the next gaming session. I've played it several times since then, always on Hard difficulty.
The game's still on my hard disk, although ever since my Mobo was replaced about 18 months ago, I haven't been able to get the sound to work.
I played through DF again a few months ago, and if you can forgive the dated graphics, it's still a good blast. Of course, it took me far, far less time to get through it - some of the levels seem really small, now, when the first time through them they seemed quite big.
Ah...fond memories.
I can't wait to play the Dark Forces mod that's in development. Having played the 'Secret Base' demo level, I know the quality is excellent, and the mod will be very good. Of course...there are no sound issues, either.