Apolyton.net, the civilization community site, has released their review of Galactic Civilizations II: Dark Avatar.  The review, written by Solver, is amongst the most detailed out there.

It includes a great deal of positive feedback as well as constructive criticism with the final score being a 9.2 out of 10.

Even if you already have the game, it's worth checking out to get another point of view on the game.