Though GC2: Dark Avatar isn't eye-popping by any measure, the ability to customize your ships is spiffy and people have come up with some amazing designs.
Great AI, good research system, lots of decisions and choices to make. Strategies really range from anything like early conquest with a war-focused race before it falls behind the tech curve, to dominating the political, economic, or technological arenas. Dark Avatar is quite possibly the best 4X game ever.
Though it does some things rather oddly, in general the interface is crisp and clean.
Once the later stages of a game are reached, performance really begins to take a hit.