Look, from my experience (on the PS3, so thanks for all the PC jingoism) DA2 is as thus:
Less character customization: 3 classes with slightly different story dynamics compared to Origins six origins, human only compared to Origins three different races.
Less story: the fact that the game is shorter than Origins should be proof alone, but consider that the entire first act is all about getting money as a driving goal, in order to force the player into going through the main quests. Simply put, the premise, though ambitious and imaginative, was poorly executed and the story as a whole suffered for it. The companions are also very weak, and oftentimes not engaging.
Fewer features: fewer talents, no skill trees, fewer dialogue options, no ability to change companions' armor, fewer dialogues as a whole.
Fewer resources: animations were copy-pasta from Origins, and dungeons were used again and again with little to no variation in all instances, no ability to change companions' armor allows them to save on rendering other models, dialogues restricted to a Good, Neutral, Mean dichotomy.
Overall, there was a lot less. The combat changes I could care less about; I didn't mind it in either Origins or DA2, but there is a lot here (or rather not) that suggests *heavily* that the game was a victim of rushed or even - dare I say - careless development.
The fact that there was DLC available for purchase from day one indicates that the entire process was simply a cash in. I personally blame EA for this, not Bioware, and hope that a future title in the Dragon Age franchise receives a lot more care in development.
As an aside I was really hoping that decisions made in DAO would have more significance, seeing as the developers claimed as much. I saw no references to past events that couldn't have been chalked up to a good estimate of what happened. I was really hoping that certain events from DAO implied or stated to have greater repercussions would indeed have repercussions.
Case in point, Anders stayed in the Wardens in my playthrough of DAO, something that was considered insignificant by DA2. After all, didn't the writers promise they would not impose their own "canon" on players?