My feelings about Dragon Age: Origins, and generally Bioware games as a whole lately, is that the Script writing is excellent. The Story Writing, however, is terrible. I have a feeling as to why. With time deadlines, and large teams, there isn't any one person who writes the story. In every one of their games lately, there are several disconnected parts. Planets in Mass Effect and Knights of the Old Republic, Cities and towns in Dragon Age. In these, Everything; every quest and storyline event, is internally contained and does not have any effect on anything pertaining to the other modules of the game world as a whole. This is done to make the game Non-linear, such that the main story threads can be tackled in any given order.
The fact that these are so disconnected means that the writing team can be divided and each segment can be written individually by different teams. While obviously, there has to be some overlap to combine the whole to respect the presence of certain characters, most of the time the majority of party members that you acquire after the first linear bit, or whose acquisition is optional, may as well not exist, or are only given token throw away lines. This is also the reason why only the beginning of the game has real coherency and the ending often is the most linear, where the most railroading is. The beginning, everything is very well defined and there are few variables that the player could have effected, if any. The ending, there are so many variables, keeping track of every possibility, and making them flow together in a coherent and natural way is nearly impossible. The inclusion of DLC just further confuses things.
Take, for example, how regardless of Character class, the way the Player Character kills the Archdemon is always the same, even if they've never touched a sword in their lives.
Further, often the stories have Idiot Plots. Plots that rely on one character or another abjectly refusing to confront facts or ignore what's staring them in the face to create melodrama. The Council in Mass Effect is case in point. This is made even worse when they would rather believe transparently evil characters like Saren, or Lorghain. Again, I feel that this is a case of railroading, necessitated by the modular nature of the story that permits the Player to take quests in any sequence they care.
When it comes down to it, each individual story, the main storyline quests, are fairly good, internally consistent, and well written. It's when they attempt to tie them together that things begin to seem far less meaningful, far less interesting. At least to me. You finish one of the storyline quests and it seems like, "Whelp, that's done, lets never talk about it ever again."
The worst thing to me is how important these main quests are painted to be, how critical accomplishing them is, only to see absolutely nothing come of it aside from a few off hand references in the final quests. Mass Effect 2 kind of got it right, in that there was a clear possibility for degrees of success and failure, but it's never clearly obvious why you succeed or fail.
I feel the problem is that there is an industry wide resistance to making storylines internally contained, in favor of leaving things unresolved on the faintest possibility that their works can be turned into a franchise.