Yeah, it's fine? As will become tradition with Capaldi Christmas specials, it has a fantastic final few scenes - in this case, the sleigh ride and the Doctor talking with elderly Clara - but the episode beforehand takes a little too long to properly get going and then keeps repeating itself; and not really in a creative way. It's just replaying the same beats it had presented before.

Santa's there... just because? Ah well, it's only just a dream. OR IS IT? Also the inclusion of Danny Pink is a really nice coda for Clara's story in S8.