I'm a little disappointed with the direction they took with the Oswin character.
Don't get me wrong, I loved both her appearances so far, and perhaps the stories wouldn't have been as good if they gone the other way, so I'm not sure if I should complain about this at all, however I see one great opportunity that was missed here.
In The Snowmen, she played an inspiring character of Victorian time. Instead of turning her into multi-dimensional technobabble mystery herself, they could have taken her on the journey where she was the one who was mystified by the future. I don't care that much to be mystified as a viewer. They could have taken her exploring the wonders of a universe that's foreign to her both socially and technologically, and mainly from the more human point of view. At a very slow pace, starting from Madame Vastra, taking it slowly to the 21st century and then jumping straight into the rest of the universe. And in the end, her transformation into the other Oswin we saw could have been more human in nature too, like Donna but more down to Earth.
Clara's time of origin and Coleman's charisma would have worked wonderfully to depict this kind of journey, and sadly they blew it. A shame. I'm also not sure I'm happy with how they fractured her memories. Hope they manage to pull out some nice trick to glue them together. That would be rather nice.
But eh, I think I'm going to love this regardless. It's going to be good either way.