Alan Mattli’s review published on Letterboxd:
I think Branagh's biggest mistake here is that he seems to think he can make Poirot and the world he exists in the stuff of legitimate drama, or at least that's what that funeral dirge of a final ten minutes suggests to me. But it's a pretty unavoidable fact, and one that Agatha Christie knew perfectly well, that a pompous crime-solving Belgian with a silly mustache and an even sillier accent does not lend himself to emotional, character-driven storytelling, beyond what is relevant to the case at hand.
Murder on the Orient Express understands this, and so does Death on the Nile, in places: far and away the best stretch is when Poirot gets to investigate his way through a once again wonderfully contrived mystery (set amidst a bunch of extremely ugly green screens); and even though the parlour revelation is underwhelming in what it ultimately delivers and held back by a tediously self-serious "this time it's personal" tone, the sheer theatricality of the staging makes it quite a rousing scene nonetheless. Even the mustache origin story which opens the film (and which has better black-and-white cinematography than the entirety of Belfast) kind of works because, for all its ridiculous pathos, it seems in on the joke – another example of Poirot's curious brand of narcissism.
But alas, just as the ending eventually demands we take this prologue seriously, so does the entire first half of the film delude itself into thinking anyone but Poirot is interesting enough to work as a character rather than a storytelling function. As a result, large portions of this are fairly boring – futile attempts to flesh out characters that don't need fleshing out, with Poirot's forays into inept romancing being perhaps the biggest nuisance of them all. And because most of the performances are varying shades of bad (Gal Gadot, my god), watching these one-note characters do nothing isn't even fun in a meta sort of way.