So, it seems this thing is about 20 hours long, longer or shorter depending on your success and how many side quests you complete. It's really more like Dragon Age Origins: Gaiden than a continuation of the original story. Apparently that will have to wait for the sequel, this is just a small tale in the life of your character, possibly for the length of a week while he cleans up this Arling. You learn a lot about the Darkspawn, and you deal with political intrigue, but it all feels like they could have gone a little bit further with it. Most of the loose ends that you would hope to play through are explained away in the final cutscene as it tallies the results of your activities and the fates of your party members. It's a great little interlude for the player craving more of the same world, and it definitely whets my appetite for whatever comes next, but I just wish had been a little bit more fleshed out in certain areas.
One area that it did flesh out to my great satisfaction is the skill trees. There are two new specializations available to each class, and a new line of talents in each of the martial trees available to rogues and warriors, putting them more in line with mages in terms of options and end game power.
Overall, good enough that it left me desperately wanting more.