When last I played it (a long time ago, and not with the latest expansion, but it was with Dark Avatar, the first expansion):
Did I already say this? Not sure. Well, if not:
GalCiv II had no soul, the tech descriptions were horrible, the tech tree itself was horrible, and the game design was horrible. By that, I mean that there was no way to intercept ships in movement during the enemy turn (in non-tile-based games like MoO II or SoTS you can intercept them long before they reach your systems, or they are forced to fight you when they arrive), and if they fly past your defense fleets in one turn it was impossible to keep a defense fleet at a planet to defend it unless you built a specific building to allow them to function as a fleet. If you didn't, every ship fought a separate battle, resulting in them being easily taken out one by one, which made no sense because you didn't need to build anything special to have fleets anywhere else. (What actually happened to make me quit the game forever was that I did this to an AI. I made warships and transports with so many movement points that I could fly them from our borders to an AI's planets in one turn, and built enough of them that I could take out any ships sitting at his planets in one turn and capture all his planets, causing all his other fleets to disappear and removing him from the game. I moved them to the border in one turn, he warned me that they should not be there, and then I declared war the next turn and eliminated him. Then I quit because it is just terrible that the game even allows that. I think Stardock's reasoning was that the AI on higher levels should call you on moving units next to their borders, and declare war if you do, but if anyone can build fleets that can cause one turn game overs for anyone else, you can't balance it by making the AI more paranoid...)
As a result of GalCiv II, I was wary enough to not pre-order Elemental, and after Elemental came out and they sold Impulse to GameStop, I wrote off Stardock entirely.