WARNING: MAY CONTAIN SPOILERS.
I finally watched the second part of The End Of Time on iPlayer yesterday. I couldn't see it live and I've avoided commenting on this or reading anything about it in the press or on blogs until I'd seen it. As many have pointed out, avoiding David Tennant has pretty much meant avoiding the entirety of human media output over the past month.
The End Of Time is the swansong for both David Tennant and Russell T. Davies. Interestingly, the main plot is resolved just over halfway through the episode and the rest is taken up with the highly ironic (and contrived) situation which leads the Doctor to regenerate, and with the Doctor, knowing he only has a few hours left, travelling around saying goodbyes to key characters. It was a bit like the end of Lord of the Rings in this respect, although I think it's just about justified here for several reasons.
Over at io9 there's been a fascinating discussion about all the unanswered questions in this episode - this is deliberate as the questions or hints are actually voiced by characters in this or previous episodes - and I read this straight after watching as I felt desperate for more Doctor Who. I'm surprised to admit to myself that this has been emotional.
What I've been thinking though is that regeneration is treated much more seriously than in the past - when old Doctors regenerated (I'm old enough to remember - in a vague blurry way - the end of the Tom Baker era and the arrival of Peter Davison) it was traumatic, possibly painful, quite trippy, but it was still basically a healing process. Tennant's Doctor portrays it more as a death and rebirth - does he literally mean that he dies and a new Doctor grows in his place (like a butterfly replacing a caterpillar) or is this more metaphorical? The latter would work - this Doctor has spent longer in his body and personality than the last few regenerations and would be more attached to and identified with it. Along with this comes a powerful blurring of fiction and reality - the sadness of both the actor and character on their leaving behind this part of their lives after such a long and intense period, together with similar sentiments from the writer/creator and perhaps from viewers? This is a huge event and it takes place both within the Doctor Who universe and here in the real world.
Matt Smith's appearance was yet another Douglas Adams reference: based on the scene where the sperm whale, brought into existence by the Improbability Drive, has just a few minutes to make sense of the universe before realising that he is about to crash into the planet. I also liked the moment where he thought he was a girl - referring to the predictable debate that happens every time the BBC are casting for a new Doctor. You'll get no more Matt Smith comments from me here, I can't really think about it at the moment so I'll be waiting to see how the new series pans out.
Overall I though The End Of Time was one of the better episodes from the Russell T. Davies era although nowhere near the best - there are many wonderful, right notes (the moment when the Doctor hears about the Time Lords and instantly takes the gun!) but also some wrong ones. However fittingly enough this is definitely Tennant's best performance and as it was so moving I don't mind the overlong goodbyes after all - they both fit the character of the Doctor and have been earned by the actor.