This is my reaction as copied from a Spooks forum. I can't be bothered to dissect any more, I'm just far too angry.
I have to say, I've never been more angry about an ending. Someone on [the Spooks forum] the other day said that the actors must never become bigger than the show... isn't that what just happened? The entire last ten minutes were a farewell to David Tennant and his tenure as the Doctor, they added NOTHING to the story or even to the characters.
I have been a huge David Tennant fan and I really enjoyed tonight's episode. It was a good romp, lots of fun, thoroughly confusing at the end, but...
I feel thoroughly ripped off. He deserved better.