There was certainly something reassuringly Doctor Who about this episode, whatever era of the show you might happen to have cut your teeth on. If you were a big Russell T Davies fan it might have been the completely contemporary OAPs mingling with "Hyph3n with a three" and the green-haired handyman family, but "Classic Whovians" were also served up with besieged bases, Earth underground stations on "alien" planets, and corridor-running-pursued-by-monsters aplenty.
That's not to say it was all that great: weird to see someone with such a solid handle on what kind of things might be good to put in a Doctor Who episode managing to fail to construct a good Doctor Who episode. The first failing is that there are way too many characters in here, way too many, with the result that none of them gets more than a couple of minutes to establish themselves, with enormously haphazard results. Bella's "issues" may be no worse than our beloved Ace's, but if you want someone to come across as a sympathetic character despite sabotaging a holiday camp and causing the deaths of an awful lot of people in the process, you probably need to put some time in it. As it was, "Ryan clearly fancies her" was not sufficient to settle the question of her good guy status for me. (I'm well in favor of a return to the days of companions temporarily hooking up with other attractive young people in the vicinity as a plot driver, mind you.)
It could be though that the major flaw in this episode was the direction: it wouldn't be the first time that a script seemed pretty good on paper and then fell flat in the execution on Doctor Who, not by a long chalk. The conjuring up of a sense of threat was deeply inconsistent, with the oldies' respective presumable horrific deaths being played almost for comic relief, and of course there wasn't any actual time to waste on things like mourning or terror that oh my god those of us without a convenient TARDIS are all going to DIE.
The Dregs being respiratorily tree-like (ancestors of certain characters in The End of the World, perhaps?) was interesting and fitted in well with this week's Big Message about the importance of balance within ecosystems. The constant callbacks to the overarching Chibnall era theme of family was also noticeable and I wouldn't have minded it if this episode hadn't had quite enough in it already with a lightweight subplot about treating your precocious children with more respect.
Let's call this another 7/10: overall it ended up better than quite a lot of similar runarounds we've had in recent years (Smile, The Ghost Monument, Kerblam!) without troubling the vicinity of greatness at all. I genuinely think 2020s Doctor Who can get there, but it's proving to be quite a tester of patience having to wait so long for feet to be found.