Let me admit my bias first: I liked the first more than the second, but part of that may simply be more familiarity with it. As always with an internet opinion, your mileage may vary. That said, onward!

If you liked FS2, then I think you'll like FS1 too. The gameplay is the same, such that I could easily pick up FS2 after playing FS1.

I think the game stacks up pretty well, though FS2 has more variety in stuff than FS1 did. There is a bit more variation in missiles in FS2 (ex. there aren't super long range missiles available in FS1). You're almost exclusively in a Terran ship of some kind for the FS1 campaign. They don't have the same kinds of interface screw or "You're already in the action get moving from second zero" missions in FS1; you never open a mission under immediate threat.

I think the story did some mission surprises better than anything I recall from FS2, and I think they built up the antagonist a bit better (granted, they didn't have prior lore to worry about). There are several missions where you're still at the mercy of your AI companions, though. Dragons are still a pain to fight.

Also, the Silent Threat expansion campaign is kind of a wreck. There are some interesting missions, but some of them are definitely lacking. I've played it more than once, but don't expect quite the same quality that you see in the main campaign.