It's colours to the mast time . . .
Highly enjoyable to watch. It was good Christmas Day television in the spirit of recent Christmases, fairly Indiana Jonesish at points, with a fun sword-fight.
There were some nice references to similar adventures. The Hitchhiker's Guide Arthur Dent comparison was made explicit, without going beyond the Dr. Who boundaries, because both Pertwee and Baker spent parts of their first stories in pyjamas. There was also the Star Wars moment when the Doctor's hand was cut off. I liked this moment, which presented a typical problem, but solved it in an unusual way, that was not out of keeping with Dr. Who's particular mythology. It has added an element to the regeneration lore, which I feel is likely to reappear in the future. It has also left a situation with the Doctor's severed hand having fallen to earth. I suspect this will be forgotten; but it does raise some questions about what might happen if it falls into the wrong hands - what if 'Torchwood' get hold of it. How much could the hand regenerate itself - along the lines of Eldrad? The 'Torchwood' moment, with the energy weapon being fired was also There was even something self-referential, with the scene where the new costume is being chosen, being very like the one in Castrovalva, with a similar angle on the Doctor looking in the mirror shot.
I particularly liked Tennant's take on the Doctor, primarily because he seemed to so enjoy taking on the role. One of my biggest complaints about Eccles was that he seemed to be deigning to play a role that he felt was beneath him. Tennant threw himself into it with gusto. Personally I enjoyed what he did and felt that he brought something fresh to the role. I enjoyed the whole concept of the Doctor finding out who he was in his reaction to what was going on around him. How he would react to the big red button, etc. And I felt that he carried off potentially naff lines such as 'This new hand's a fighting hand' and 'No second chances, I'm that kind of man' with great panache.
As for the aliens. The evil santas and deadly tree seemed amusing and memorable and quite appropriate for the transmission slot and the 'pilot-fish' 'explanation' seemed just about acceptable. The Sycorax, or Sickbags, or whatever they were called also seemed fine, but I liked their 'helmets' (which seemed typically Whoish) more than the faces underneath (which seemed a little Deep Space 9ish). What was missing was any background as to their motivation, which seems to be a more deep-seated problem of the 45-60 minute format, which doesn't give as much time for character development as the old 4 episodes used to allow. I liked the design of their spaceship, inside and out, and although I desperately dislike the present TARDIS interior, I was pleased to see some variation on it, with the spiral staircase and the wardrobe room.
Penelope Wilton was excellent, and watching the episode through a second time showed how her final decision to do a General Belgrano on the Sickbags was fully consistent with her actions leading up to that point and was quite justified, despite what the Doctor had to say: he isn't always around to save the day and the Earth must be prepared to defend itself. I was quite pleased with the balance that was left, because the Doctor was in danger of doing a Bob Geldof and snuggling up to the Prime Minister; instead he was left as an anti-establishment figure. The whole situation was very 'Silurians', where the Brigadier blows the monsters up at the end, so it was in keeping with the history of the show.
Personally I enjoyed having UNIT brought back into play, but it was a shame that there has been no significant characters developed within UNIT - a problem due again, I suspect, to the much shorter story lengths. The added issue of introducing the Torchwood format left even less time for UNIT, but did intrigue me - why has Torchwood's staff been cut by a third just recently?
Billie seemed to do what she was required to do fairly well, which seemed principally to accept the change between Doctors. The main problem with her is that she is fairly wet as a companion. Faced with a regenerating Doctor and an alien invasion she decides to hide in the TARDIS with her mummy. Perhaps Polly would have done the same, but I can't imagine Jo Grant or Sarah Jane Smith or Leela or Ace, or virtually any of the others doing that. We have had much more positive female role-models in the past.
As for Mummy Tyler and the wet boyfriend, I find them very tedious. I suppose if they were not there we would simply end up with a succession of wet background characters brought in to do not very much, so they are useful in that they soak up these duties. But I am not in the least bit interested in what happens to them.
Overall I felt that it was 60 minutes well-spent in the company of the Doctor. The general tenor was right, with the Tom Baker Wind-in-the-Willows format, where a spilt cup-of-tea helps to save the day (or at least paves the way for courage and humour to save the day). And there were some interesting visual moments, such as the murderous spinning Christmas tree, and the eerie sight of people standing on the edge of high buildings, which had a very 1970s feel to it.
I am looking forward eagerly to seeing Tennant take a proper stab at the role in his first season. After a year of being very much at the fringes, when so many people we happy about the return of the series, I feel that there is now something for me to celebrate too.