There's always a bit of anxiety for me in the build up to a new Doctor Who episode - usually loosely based on the thought that they couldn't possibly top the previous one.
In the fourth season, I don't think there was a single bad episode, although, personally, the Doctor's Daughter was not my favourite. The series ended on a huge high with Stolen Earth and Journey's End, which saw the return of Davros, loads of daleks and all the companions from the new series. The Christmas Special was excellent, too, with just the right amount of sentimentality for the season.
As usual, I needn't have worried. Last night's episode had it all - UNIT, a mad Welsh scientist brilliantly portrayed by Lee Evans, insects who communicate by telepathy, a real prospect that the earth would be reduced to mere sand by wormhole creating swarm of metal stingrays, a flying bus (as Stephen said to me last night, this definitely tops a Ford Anglia) and promises of darkness to come.
Michelle Ryan was given a very two dimensional character to play and she did ok in the role. Lady Christina de Souza will go down in history as the unluckiest woman in the history of Doctor Who, though. At any other time in his life, the Doctor would have welcomed her aboard the TARDIS, but it's too soon after losing Donna and Rose and he sent her on her way. She did get to snog him though, so it's not all bad.
David Tennant showed exactly why he is so bloody good as the Doctor and why we're all going to miss him so much. We have less than two hours screen time of him as the Doctor left. He saved the world, making it all look so easy, making us all laugh along the way, but showed his real talent at the end when the Doctor received a very creepy prediction of the future. You could just see his face and eyes darken. Tennant deals so well with the complexities of the Doctor's character and is equally good at showing light and darkness.
And what of that prediction of the future - that "your song is coming to an end". The Ood said that to him last year and then River Song came along. Could there be some tie in with her at some point? Not sure how they'd work it in, though as she didn't recognise the Tennant incarnation of the Doctor, but she is clearly a significant part of his life and there is promise in that particular story arc for the future.
So now we have to wait until the Autumn for the next part of the Tennant Farewell.