I loved (and still do love) DA:O, I couldn't wait to play that game, and I've sunk far more time then I ever care to think about into it. DA2 was a significant disappointment to me, it wasn't a bad game, but it was I felt rushed, and was inferior to me by far to it's predecessor, to much was cut away, it attempted to fix what wasn't broken and left what did need fixing. The game felt disjointed and often to me lacked any RP motivation for the PC, opportunities for a more interesting story (such as in Act III) were squandered, I felt railroaded throughout the game, without much real choice, limited feeling of connection to Hawke or Hawke's family or companions made it hard for me to care overmuch for anything (and the whole Mage/Templar situation often felt much more simplified then it had been presented in Origins).
Now before DA2 I had not played ME2, but since they have released that game free with it, I have enjoyed it allot more then DA2 despite the fact I'm not a great fan of shooters or the conversation wheel/paraphrase. This was mainly due to the fact that there I felt Shepard actually had allot more conversation options then Hawke ever had (with the three ways to say yes thing), I could actually talk to Shepard's team and crew and get to know them, building their relationship with Shepard, rather then just when the companion had a quest to give, or some plot significant moment as happened in DA2, I ended up caring about them. And finally I felt in a few areas I could actually make decisions that changed some things. It didn't fully compare for me to what Origins gave, but it was personally a breath of fresh air after DA2.
I'll finish by say, I know the above comes off critical of DA2, it was a fun game to play, and in some areas like party banter and the ability to involve companions more in npc conversations it improved things over Origins, and I found it an ok game, but one that was personally quite lacking for me.