I personally am a bit disappointed at the Tie Fighter, even though the fact that we got LucasArts games on GoG is great.
The reason is that I grew up playing the 1995 Collector's Edition. Which is completely different from the original 1994 DOS version (which had dynamic MIDI soundtrack) and the 1998 Collector's Edition which used a completely new engine but a fixed soundtrack (and I think the shading is rather ugly). GoG will give you the 1994 and the 1998 version, which is great for player choice.
But the 1995 DOS Collector's Edition version is missing. Why is this important? Because this is the only version that also has the best parts of the 1994 DOS version including the dynamic soundtrack but also has voice-overs and dialogue for all speaking characters and briefings.
There is a lot of confusion on the Internet about the different versions because the 1998 Collector's Edition was also called the 95 Collector's Edition because it runs on
Windows 95. The only place that the 1995 DOS Collector's Edition existed was on the four game packs that LucasArts released during 1995 called the LucasArts Archives.
For reference, the X-Wing game also has a 1994 Collector's Edition with dynamic soundtrack and voice-overs which is missing from GoG. If you owned the LucasArts Archives in the mid 90s, your X-Wing and Tie Fighter versions were the 1994 and the 1995 Collector's Edition, respectively. Both are the missing versions from GoG.
There is a 10 page thread on this over on GoG forums. Link below for more details.
http://www.gog.com/forum/star_wars_tie_fighter_special_edition/wheres_the_collectors_cdrom_1995