So, to me this was basically a 3/10 special that Ncuti dragged kicking and screaming to a 6/10. Seriously, he holds this entire special on his back like Atlas, the script by itself is among the worst Christmas specials. Even ignoring the song the goblins were lame and were really not Doctor Who creatures, and their convoluted motivations barely made any sense.
But Ncuti was really good, much better then the material they gave him this episode, and Ruby is ok, I'd put her above early Rose or Martha just based on this episode. I'm excited for their season to start, while also hoping that RTD doesn't personally write many episodes next season, he's been really hit or miss in this return when it comes to writing.