David Tennant was a great actor as Doctor Who. No question. His performance in this was out of the top drawer.
But the story…oh, the story!
In his 5 year stint as show-runner, writer and producer, Russell T Davies did some great things. It's my view that he over-emotionalized the Doctor, and ruined what were otherwise some great stories. There are some holes in this story, as well as a lamentable theme of “death” – which is ill founded in a man who hasn't really died. (The episode will try and convince you otherwise, though.)
This is a fitting farewell to the 10th Doctor, albeit along with some pretty thick self-serving sanctimony in an extended farewell to the companions from the Tennant tenure. That being said, it was a good ride, and I must admit, I could hardly wait for this episode to come out. It left me feeling the way it should have – a little sad, but really excited for what was to come.