Yup! I'm catching up on the Christmas specials now, as I, for some reason, didn't watch them during my first run through (except for The Snowmen). While I like them all a fair bit, I'd probably rank those that I've seen the following way:
A Christmas Carol
The Snowmen
The Doctor, the Widow and the Wardrobe
Voyage of the Damned
TDTWATW is very good as well, not as intensive and does require some suspension of disbelief, but it was a very enjoyable watch. I found it interesting that there was no real villain, and the trees, which I had expected to fit into that role, were an interesting character to say for sure.
Voyage, meanwhile, isn't bad, but it does feel very standard, with the people being picked off one by one, etc. and the involvement of Max Capricorn was pretty obvious. Still good fun, but my least favourite of the four.