As far as I can tell it effects next to nothing. But I'm still in the third act of my first playthrough. Also DA:2 comes with 3 preset imports to choose from.
The first timeskip broke immersion in a big way since I as a player was new to the city while the character had supposedly been living there for a year a knew some people around town who were complete strangers to me. I consider that first timeskip the first sign that BioWare phoned it in on this one, and didn't give any thought to how their new story structure should force changes to the game structure, and how certain parts of the story needed to be rewritten so that the character's experience would more closely match the player's.
I don't think there is any debate among those who were fans of DA:O. On BioWare's forums there are some people who point to people who didn't like DA:O but did like DA2 as a reason to say that DA2 is a good game, but I wonder if they themselves are people who didn't like the first. I have only my opinion, but I think the only debate about DA:O vs DA2 is between exclusively ME fans and primarily DA:O fans.
My own opinion for this game is that it stinks. I initially thought it was good, if foreboding in it's implications for the franchise, especially if any changes were kept for the third game. The new wheel is a marginal improvement over the awfulness of the ME version and I hope it is used in ME3. However, during the second act I realized that apparently the PC was the only one capable of talking to other people, though I could grant that capability to others temporarily by including them in my party. Even then it never seemed to rise above small talk. In Kirkwall, nobody has a life unless it involves the Champion.
And honestly who wears the same outfit for enjoying a drink at a tavern as they would when traveling through the deep roads? Even the PC has the sense to change out of armor at home. Maybe everyone else is too poor, after all the PC didn't wear normal clothes around the house at all until he struck it rich in the deep roads.