They havent shot any of the next series yet- i think they start filming in feb.
As for the xmas spesh, i thought it was remarkably inoffensive for this sort of thing, and probably my 'favourite' since the first tennant one. It certainly looked cheaper than last year's, but benefited from having a story not relying on moffat's annoying trademark time-travelling nonsense. The dialogue was still ear-gratingly awful when he was trying to be funny, and as usual all the characters spoke with the same voice, which is par for moffat across all his scripts whether dr who or not.
But as an hour's pointless xmas day fluff it did its job, and as i say, was possibly the best since 2005.
SBT