Mixed feelings:
It was obvious to me we would see him again.
I think he was fine as the Big Bad for DA I, at least in theory, but I really wanted him to be a lieutenant. Maybe even for the big bad for DA 4. Either way works, but I wonder.
Even as the Big Bad in Inquisition it seems he had wasted potential. Again, fine, and I do not think I dislike it as most people, but could have been a lot better. In Legacy he was so compelling and such a lore bomb, the accent, the confusion, and the sense of something terrible waking up. It would have been a great opprotunity to examine two of the more fascinating aspects of DA lore, to me. But...didn't really happen.
It could have been a great examination of faith and conflicts between religions, and they touched on it. But could have really gone into it much more in depth, I feel.