The marquee items, of course, are all still there. The game's level cap will be raised to 51, and the new Bard class will be added to the game for players to enjoy. New areas and new ship mechanics are also being added to keep players engaged. But there are other new features, such as the addition of "overflow" slots to player bags, stat rearrangement for caster classes, and new performance options for older computers. It promises to be a huge patch, so before you go playing tomorrow, peruse the patch notes today.
[Update: Added the new expansion trailer after the cut.]