The AI's challenge is getting greater and greater as patches come out. In addition, many people are modifying the data files for the game to make even more challenging AI's
In conjunction with that, many people are modding the game to present different technologies, ships, weapons, facilities, etc. The game is VERY easily modified, as the data files are all in easily readable .txt files.
The graphics are not spectacular, but serviceable.
The re-playability is excellent. And if you get sick of the game, try a different modification and see how drastically that changes it.
Or you can have fun like me, coming up with different modifications and posting them out there for others to use, and then basking in the praise of others who say they love your mod...
Did I mention the game was modifiable?
All in all I love the game.
Finally, the level of support for this game is tremendous. The designer continually is working on further changes for the game, improving on many things.
Finally, it is modifiable.
Derek