Most of the press reviews for 'Twice Upon A Time' were positive:
The Guardian found much to admire in the story: "There’s so much that is good about the episode...Good jokes...Anyway, it’s funny."
The Mirror felt the episode delivered: "...An emotional rollercoaster...I'm so glad that the Powers That Be decided to bring Pearl Mackie's Bill back to the show for one more outing. In an episode that can't really escape from a looming theme of death, Bill brings not only a sense of fun but also heart to the episode."
Radio Times felt the story was lacking substance but praised the nostalgia inherent in the story: "I get a little surge of joy that on Christmas Day 2017 the BBC1 audience will glimpse clips from 1966’s The Tenth Planet of William Hartnell and Michael Craze, both long dead, and Anneke Wills. The lamentable recast versions of companions Ben and Polly are kept mercifully brief, but in a coup of televisual magic a monochrome Hartnell transmogrifies into Bradley in HD colour. The first Doctor rematerialises right before our eyes."
The Independent praised the two lead actors: "Peter Capaldi, as ever, turns out an incredible performance as the Twelfth Doctor...David Bradley steals the show as the First Doctor. "
Digital Spy felt the episode delivered where it needed to, also praising David Bradley's portrayal of the First Doctor: "His performance really is spot on – a little spiky, pompous, yet warm and humane...You're left hungry for more – for a story where Bradley's first Doctor is more than a distraction from the main event."
Den of Geek felt the acting plaudits belonged to one of the guest stars: "I can’t overstate just what superb work Mark Gatiss does too, as The Captain...Gatiss’ quiet, diligent, matter-of-fact performance was tinged with a melancholy edge. Appreciating he had to do some of the ‘what are you talking about’ dialogue to the Doctors, I thought he played it superbly. Polite, baffled, and quietly curious."
AV Club felt the episode was a fitting tribute to the Twelfth Doctor: "This is a thoughtful, funny, incredibly moving episode about kindness, bravery, and the way small choices can make a huge impact... it gives Peter Capaldi a beautiful final showcase that demonstrates just how much he’s grown into the role since his rather ominous beginnings back in season eight."
IndieWore thought the regeneration was too drawn out: "The tradition of the Doctor pushing back against his regeneration is a recent one, and it makes for a prolonged and unnecessary goodbye. Regenerations are at their best when we’re tricked into forgetting they’re coming"
iNews praised the writing of Steven Moffat's last story: "The sharply-written interplay between both Doctors was one of the joys of this episode."
Inverse found the episode a fitting final appearance for the twelfth Doctor: "“Kind” is the defining word for the 12th Doctor... That the incarnation who began his existence so prickly and aloof would end it as the champion of kindness speaks to just how much this Doctor grew and developed over this three seasons."
However, The Telegraph wasn't impressed: "Heavy on stagy dialogue and light on action...ultimately, even the hero admitted there wasn’t a villain."
And, of course, The Daily Mail found the episode wretchedly dull: "We had to endure an age of Capaldi wringing his hands and begging humanity to ‘be kind’. David Bradley reprised the First Doctor...His chief role was to make scandalising remarks about the importance of having a woman about the place to do the dusting, and to look horrified when Bill Potts (Pearl Mackie) hinted she was a lesbian."
Doctor Who News - Twice Upon A Time - Press Reaction