I have this game and have mixed feelings...
The idea is great, and some things too (damn, is like to play several Civilizations game at the same time!), but because is a very complex game, obviously the AI is very weak. Have several bugs, the units have unbalances, and the replay value is weak too (the planets are always the same).
Some guys have modded the units, and then, balanced a lot the game:
http://website.lineone.net/~rwein/nova/home.htm
Is a good game to play by e-mail (I have played only one, against a guy that knew here: Possum), but the players should try to agree to do not use the game bugs in their favor (see into the Nova website, the House Rules).
Considering that you could purchase the game for a little money, I think that you could try it.