This is still a pretty good game, but it's lost a lot of the magic of Origins. It lacks the emotional and dramatic depth that made Origins so awesome. The companions, who were crucial component of Origins, aren't as good, and you can no longer engage in long and in depth discussions with them. If you enjoyed listening to Zevran tell tales of his time in the Crows, or the bonding moments with Alistair or Leliana, that's pretty much gone. There are still conversations with the companions but they are triggered here and there automatically and are very short. There are no romances, and much to my dismay no mabari companion.
The balance of the game has been drastically altered concerning the difficulty, the rate at which characters level up, and the amount of loot. The combat is much, much easier. You should definitely up the difficulty one notch from whatever you played Origins at. Additionally you seem to level up at the drop of a hat, and so levelling becomes meaningless. By the time you're three quarters of the way through you'll be assigning your talent points on disciplines you don't even use. I think it's too easy to find gold and there's too much loot. There seems to be some valuable piece of gear in nearly every crate you look in. I had over six hundred gold by the end and didn't have a thing to spend it on. The way Origins balanced these elements was one of the things I was most impressed with, and one of the main reasons I found it so enjoyable. So many games mess it up and have you levelling way too quickly and getting rich very quickly. Origins was one of those rare games that balanced those crucial elements almost perfectly. They have either not taken nearly as much care with this game, or they deliberately changed it, which is a real shame.
More effort could have been put into the side quests. And I was annoyed by all the stupid quests that had me running from one end of an area to the other searching for objects, notes, clues, statues or what not.
A minor irritation for me is the burst of blue flame that engulfs a character whenever they get a kill. The screen is already too busy with all the coloured rings and spell and talent effects. Plus what is it supposed to be anyway?
I did like the addition of paint potions that you can use to apply heraldry to shields, such as the grey warden coat of arms or the Cousland emblem.
And I of course liked that it's more Dragon Age, and as far as I'm concerned you can't have too much Dragon Age. It's still pretty good, it's just not as good as the original. I guess try to keep in mind that it's an expansion and not a sequel, so you can't really expect it to be as good as a full game.