The first review of Galactic Civilizations II: Twilight of the Arnor has arrived and it's from GameSpy.  Mega reviewer Allen Rausch has taken an extremely in-depth look at the game and put together a very detailed review.

Here's a quote:

The technology trees alone make it impossible for someone who's sampled Twilight of the Arnor to ever go back to just playing Dark Avatar. Add to that impressive customization tools, new gameplay dynamics, better AI, graphic upgrades, new ship-builder components and completely re-done flavor text and hundreds and hundreds of smaller tweaks, fixes and changes and what you have is an absolute triumph and a new standard for turn-based-strategy games. Bravo, Stardock. This is how expansion packs should be done.

Please check out the review for yourself!