IF 2009'S DRAGON AGE: ORIGINS was a sprawling Dungeons & Dragons campaign, Dragon Age II is a George R. R. Martin fantasy novel. Everything has been streamlined, focused, and refined, making for a sequel that plays quite differently from its predecessor—but also one that tells a much more gripping, thrilling tale. After all, isn't that what BioWare is going for here?
You want details? All right. The biggest change in DA2 is the combat system. Where the original felt like a well-intentioned but ultimately clunky mash-up of BioWare's Baldur's Gate and Mass Effect combat systems, killing stuff in DA2 is almost action-game easy. It's quite impressive that BioWare was able to devise a system that loses none of the complexity of the Dragon Age skill tree (and actually increases it), while also making it entirely possible to simply mash buttons and watch stuff die all around you. It's a stunning example of appealing simultaneously to the casual and hardcore crowd, and should be applauded.
The other great change is in the game's overall narrative focus. Origins allowed you to pick a number of character archetypes in an attempt to offer players the same sort of "build your own adventure" freedom found in a pen-and-paper role-playing game. Dragon Age II, on the other hand, still allows you the choice between playing a warrior, rogue, or mage, but also essentially says, "This is you. Live this person's life." It's a design choice that could upset a lot of role-playing fans, but the story BioWare presents within this framework is such an excellent example of high fantasy that I doubt many people will mind.
I realize it sounds like I'm overly praising this game, but if you were expecting a long list of negatives, you must not be all that familiar with BioWare. They're in the business of making grand epics—and, technically speaking, Dragon Age II is their best effort to date.