Reading a play that you've never seen performed is a bit of an awkward experience, because you have to imagine pretty much every interpretative thing that makes a play come alive when acted, from the stage setting to the actors' vocal inflections, behaviour and the clothes they wear. In this particular instance, at least I had the visuals of two movie adaptations of the underlying novel to fill in the void (plus my own memories from a trip to Egypt 10 years ago), and Agatha Christie -- ever the novelist -- also gives incredibly detailed stage directions both for the setting and ligihting of the stage and for the actors' movements(show spoiler)
But absent seeing this play performed, there still seems to be at least one layer of complexity less than in the novel Death on the Nile; and not only as a result of the reduction of characters and the elimination of virtually all subplots, with the sole exception of the second (pseudo-) love triangle involving a young female passenger harrassed by an overbearing elderly relative (in the book: Cornelia Robson), a socialist aristocrat who has dropped his title, and a German-born doctor and psychologist who happens to be among the passengers (here as in the book, Dr. Bessner).
Moreover, as Moonlight Reader notes in her review, absent a few bead sellers appearing at the beginning of the play and a minor blackface character appearing throughout (the boat's steward), this play could be set in England or anywhere else in the world just as easily as in Egypt. Essentially, this is a cozy / drawing room mystery, whereas in the underlying novel the Egyptian setting is a crucial, indelible element.
I'm also not sure that the elimination of Poirot and the conflation of the roles of the detective and of the murder victim's guardian in a single character named Canon Pennefather* really works for me (or why the inclusion of that guardian was necessary to the reduced framework of the play to begin with -- or why he has to be a Canon, for that matter). Obviously, Poirot's lines about not letting evil into your soul (when speaking to Jackie) are perfectly placed as coming from a clergyman. But we don't ever see a response from the good Canon that suggests he is shocked, distraught, sad or in any other way personally emotionally touched by his ward's murder -- he instantly accepts the captain's request to act as investigator (and why that part should be in better hands with him than with the captain himself beats me as well, since it actually would be the captain's job under the circumstances), and we see the Canon acting in the capacity of detective only pretty much the whole time from that moment onwards.(show spoiler)
All of these implausibilities don't amount to plot holes large enough to sink the entire play, and come on, this is still Agatha Christie. I also suspect that a good production of the play would be able to re-supply quite a few layers of the depth stripped away in the text of the play vis-à-vis the novel (especially if the actors and director involved had read the novel). Even so, this is at best Death on the Nile Light.
* Again as MR notes, not the same person as the Canon Pennyfather from At Bertram's Hotel. Not only do the two gentlemen exhibit entirely different, even diametrically opposed characters (and spell their names slightly differently); there is also no reference in At Bertram's Hotel suggesting that the Canon Pennyfather from that novel could have any connections with Yorkshire or Shropshire.
Nile cruise ships moored next to each other at the pier in Assuan (above) and at Kom Ombo temple (below)
Abu Simbel: Entrance to the temples of Ramesses II (above) and his queen consort Nefertari (below)
(Abu Simbel is -- supposedly -- the setting of the play's second and third acts)
On the Nile: Near Assuan (above) and near Luxor (below)