The Official BBC Doctor Who Site have a brief article where Matt and the Moff give their thoughts about "The Snowmen":
Starring Matt Smith as the Doctor and introducing Jenna-Louise Coleman as Clara, his new companion, this year’s Christmas Special is called The Snowmen and follows their adventures as they battle the villainous Doctor Simeon (Richard E Grant) and his army of sinister snowmen.
It promises to be a movie-scale episode and aside from Clara’s debut and the return of Strax, Vastra and Jenny, The Snowmen introduces a new look for the Doctor and a new monster that will have families shivering behind their sofas.
Steven Moffat, Lead Writer and Executive Producer, said, ‘The Doctor at Christmas is one of my favourite things - but this year it's different. He's lost Amy and Rory to the Weeping Angels, and he's not in a good place: in fact, he's Scrooge. He's withdrawn from the world and no longer cares what happens to it. So when all of humanity hangs in the balance, can anyone persuade a tired and heartbroken Doctor that it's time to return to the good fight? Enter Jenna-Louise Coleman…’
Matt Smith, who plays the Doctor, commented, ‘For this year’s Christmas Special we have the wonderfully villainous Richard E Grant as Doctor Simeon. As well as lizards, Victorian assassins and deranged warriors from the future all return to convince the Doctor that he should board the TARDIS again and save the world. Add to that Jenna-Louise Coleman and so begins the Christmas Special, 2012. I hope everyone enjoys it!’