I think you may have suffered in your enjoyment of this episode from having thought too long and hard about the series and being too knowledgeable about the backstory. I really enjoyed it, because I'm not an involved fan so most of the references and explanation linked to to things I'd half-forgotten.

I didn't mind Rose's character change. One of my gripes with Rose was that she went through a lot of quite traumatic stuff and it didn't seem to hit her in the way that I'd expect it to. It seemed right to me that at last her experiences had hit and changed her, particularly the being Badwolfed: surely that's not something you should just walk away from with a cheery chavvy wave.

Original Donna, I am with you. What a pain she is.