I remember I started playing Freespace 2 for the first time back in 1999 and thought how awesome that game was, so when I came across the first Freespace game in a store I just had to pick it up. I haven't played the GOG version so I can't comment on weather anything is different or not.
Visually not as stunning as Freespace 2 due to only being able to select 640x480 as a resolution (not sure about the GOG version, maybe tweaked to go higher?) but the graphics are still nice anyway. It still has all the lovely nebula's, star fields and sun flares etc and the textures are actually not that bad, considering the resolution, if it could go any higher then it would look as good as Freespace 2.
Gameplay wise Freespace 1 handles pretty much the same as the second game, which is good and the HUD layout is very similar also, so if you've played the second game then you'll be right at home here control wise. It is also a very difficult game in parts as some missions will have you pulling your hair out if you play it on hard.
The story is very good also, very compelling, with a sense of foreboding and urgency. There will be some very tense moments in this game.
Overall a very well polished game, about the only downside is not being able to select a resolution higher than 640x480.