Dragon Age - Extensive Preview @ GameStar.de

Moriendor writes in with this German Dragon Age preview at GameStar, which I've called "extensive" because apparently the author has actually finished the game.  Heavy spoilers apply, I'm told.  Moriendor also adds:

There is an interesting bit in the comments thread. When asked how long it took him to finish the game he said that it took him approximately 30 hours to finish the game when he focused strictly on the campaign (on normal difficulty). He is now replaying the game on hard and he is going to try to do all side quests on this run. His estimate is that it should take him "significantly longer" and he guesses at 40 - 50 hours.

In summary he thinks that a single playthrough should take around 30 to 40 hours but if someone were to play all Origin stories and to solve the campaign and quests in all available ways and if you were to go after every single achievement then the game should keep you busy for well over 100 hours.