I definitely think Flip-Flop is a little underrated but I do understand its limitations.

The design and clever use of time travel is a major highlight of the audio, to the extent I would consider this a pretty much must-listen for Doctor Who fans. The cool structure of the audio is really novel even among a long-running franchise with lots of crazy time travel, non-linear stories. It reminded me of the Big Bang in a good way, or a much, much better version of Ravagers. This is among one of the better ones, even if the story itself doesn't have much of a point, per se. It's a bit of a paradox that doesn't really get much of a satisfying resolution. This world the Doctor and Mel visit is essentially facing two versions of doom, and no matter what they do, they are basically screwed.

That feels mostly on the Slithergee, who essentially weaponize playing victim against the humans in such a way they are able to decimate the world of Puxatornee no matter what happens. All this and more I found really clever. Mel also gets to really shine here.

Where the audio is limited is more around some of the other characters. Mitchell and especially President Bailey felt way more off in their writing, with Bailey's whole affair feeling very silly both times around. Stewart and Reed were also more annoying than anything else.

I also agree with PalindromeRose, who, by the way, is one of my favourite Doctor Who reviewers, where the story could at the very least be interpreted as having some pretty heavy right-wing themes to it. This is something I definitely noticed, and it even has that particular flavour of modern conservatism that feels deeply rooted in a macabre sense of cynicism I kind of despise, but, I don't know. I didn't feel it was part of the authorial intent and didn't particularly get the sense that this was supposed to have politics meant to be taken that seriously. The Slithergee felt menacing more than a political statement.

So, overall, an imperfect but kind of legendary audio. The Christmas connection was threadbare, though, to the point I'm not really sure why they bothered.