In the days where X3 rules the space sim arena- small as it is- this game still stands out.
Oh, and the graphics are still excellent by today's standards. I have yet to see a game with better explosions, and the stellar vista is comparable if not superior to that of Eve Online.
The sound effects are very good in this as well; the sound effects are, as far as I can tell, largely unique and not used in other games; the "sound echoing in space" effect is great- just listen to your ship smack into another one, or a swarm of Harrower Missiles emit their distinctive pitch. The music is absolutely amazing; It's a great blend of cosmic resonance a la Homeworld, with bass string instruments thrown in for good measure. It's pretty hard to describe, but you'll be hooked to it in no time.
I'm giving this straight tens because it is, to me, a flawless package- a game with focus, polish, and thoroughly baked goodness. It's even got a great slew of mods from the community. So many games these days try to hit you with lots of great features, but they all lack cohesion; it's like watching a good movie or reading a great book... this has a well defined plot, and nothing feels like it was just tacked on either halfheartedly or uselessly. Along with TIE Fighter and Heavy Gear 2, this game has held my attention longer than any modern "epic".
Make sure you have a tri-axis joystick with a POV hat, though; that's half the experience.