My initial reaction is that it was pretty good - not in the top tier of Christmas specials, but pretty good.
I would imagine that some people might not appreciate the lockdown stuff, but I don't think it was pushing any kind of agenda - just acknowledging that there were some tragic side-effects of that whole situation.
What really struck me was how well the episode fleshed out Joy, Anita, Trev with fairly limited screen time. Ironically, Joy was probably the least fleshed-out, but Nicola Coughlan played the part very well.