Well, it is just a new zone, like any other zone there is.
If you are going to give DAI a new playthrough, you can get it so you can visit a new area instead of the areas you already know.
If I were to do a new playthrough of DAI, I would definitely buy it, since 15 dollars is not money for a working guy like me, it is not much money. And instead of doing crestwood, or oasis, or whatever zone I have already visited, I would do this new zone.
However, I still need an incentive to play the game again. This DLC is not giving me the needed incentive to do it.
So I will wait for a story DLC, something that makes me wanna play the game again, and then instead of farming power in already known fetch/side quests, I will do it in this new zone.
So its up to you Bioware. Do a good DLC and its +15 dollars inmediately from my part. But this DLC is not good enough still.