The moment that Doctor Who became a Christmas TV institution. David Tennant properly takes over as the Doctor in this fine episode that has a lot to do, but mostly pulls it off excellently.
It's Christmas, as the Tardis crashes back to London and the weak, still regenerating, Doctor (David Tennant) stumbles out into Mickey's (Noel Clarke) arms. Whilst he's recuperating at Jackie's (Camille Coduri) flat, Rose (Billie Piper) is attacked by someone tracking the immense power that the regeneration is giving off. Meanwhile a Mars probe in intercepted by the Sycorax, whose warship is heading to Earth, causing now Prime Minister Harriet Jones (Penelope Wilton) to consider drastic action.
As much as I enjoyed the Christopher Eccleston season, David Tennant is probably "my" Doctor, so despite him sitting out a lot of this episode, the moments at the end, when he appears to save the day, are thrilling (even if the "fighting hand" line is a little cringy). He looks strikingly young in this (still not quite young enough to be romancing Billie Piper, but closer than Eccleston was). There's enough carry over from Eccleston's performance to sell the idea that they're playing the same character, though one going through changes.
Having got off to a flying start, introducing the Tardis crashing and Tennants comedic timing, the episode actually drops off a bit. The scenes involving the spinning Christmas tree and the Santas both feel similar to the debut episode "Rose" and crowbarred in to make the episode more Christmassy. It's not until The Sycroax, including a heavily made up Sean Gilder make their appearance, and make their horrifying threat visible, that the show picks up again. There's another early role hidden here, with "Peaky Blinders" Arthur Shelby, Paul Anderson, in his first TV credit as one of the key characters to fall under the Sycorax spell.
It's quite a funny episode too, running gags about people knowing who Harriet Jones is now, play back into her previous episodes and work well and despite the fact it's got an awful lot to do, the episode pulls most of it off admirably.