The last two Doctor Who episodes featuring David Tenant were distinctly underwhelming, I thought. I don't think it's good writing when, in about 130 minutes of television, you only have the plot explained at about the 80 minute mark.
In fact, it's pretty clear that Russell T Davies stayed on about a season too long. (I never took to Donna.)
It will be interesting to see where the series goes from here, though. I do hope we get an end to things like the Doctor playing cupid to gay guys, which was one weird little aspect of last night's show.