To me, though, that wasn't what knocked me out of the episode. The worst, the absolutely horrifying and freakish stuff, was the bit with Other!Ten and Rose. The Doctor has a one-off human hybrid version of himself, and at the end he takes Rose back to her parallel earth and tasks her with looking after said hybrid. Who is slightly unbalanced and bloodthirsty. And says, basically, "Here; go fuck him."
Really? I mean, *really?!*
I could have accepted it, maybe, if the idea had come from Rose; if she'd seen something that made her think about the futility of living life with the real Doctor. Even if it had come from Other!Ten, saying, "Look, he can't give you what you want -- me, I can." But no, it's Regular!Ten who presents this as a fait accompli. We needed something there -- Ten talking it over with Other!Ten, or a scene with Rose and Sarah Jane where Rose sees how Sarah has fashioned a new life, a real life, outside of the TARDIS. This just felt horrifying and creepy, and it disturbed me so much that Donna's sad end was almost a relief. At least her horrible fate was, in character terms, the Doctor's way to save her life; that's sad, but I can deal with it a lot better than I can with a supposed happy ending that comes about because the main character can't be bothered.
But then, I'd always thought that the good way to handle Rose's relationship with the Doctor would be to give the shippers what they want. One episode an unending Doctor/Rose schmoopfest, going through the years and whatnot, with Rose aging all the while and finding it harder and harder to run hand-in-hand, until she finally drops dead from old age. She gets exactly what she wants, and the end still sucks.