The game is already released in the US.
Dragon’s Dogma: Dark Arisen has received a launch trailer and it shows what you can expect from the expansion. It contains the original game as well as new stuff. The game has been reworked as well and rebalanced.
It adds “an entire island of new dungeons, quests, equipment, items, and enemies (including giant bosses).”
Players who own the original game can get a bunch of in-game bonuses like infinite fast travel item when they use their save with Dark Arisen.
The game is already out in the US and will be released on April 26th in the EU. It costs $40 and is available as physical and digital version.