Hi, Campy,
Sorry for not replying, haven't been here in days...busy as you might suspect
I will try to setup an email notification to respond faster, until we get more regular traffic here.
I did not take any features out of the demo, except a limit that you cannot go beyond sector 7. (The soundtrack was removed for the purpose of keeping it small).
A full game of Approaching Infinity might take you across 50-100 sectors, or considerably more if you just want to explore. (it's also possible to win by only reaching sector 20).
So, a great deal of content is revealed over time. New kinds of sectors and planets, new enemies, new devices, new terrains and even different kinds of weapons and shields, etc.
Also, it is possible to befriend each of the 12 sentient alien races, and complete their quest lines (though not all in the same game). This takes time and careful play, especially in some cases.
So I would say the demo gives you enough time to learn how to play the game, but the full version will give you very many more reasons why to play it.