This movie was clearly made for a modern audience with no familiarity with Agatha Christie's work. Branagh's portrayal of the legendary Belgian detective Hercule Poirot bares only a passing resemblance to the source material with an inconsistent accent, the wrong mustache, and only some of his iconic quirks and mannerisms. That being said, it is a decent mystery that follows the plot of the story pretty well and it would probably be enjoyable to people seeing the story for the first time and having no preconceived notions of what Poirot should be.
A strong supporting cast featuring Michelle Pfeiffer, Daisy Ridley, Johnny Depp, Willem Dafoe, Judi Dench, Penelope Cruz, and many other familiar faces performs well. However, no one stands out in the way Ingrid Bergman did in the 1974 adaptation or Jessica Chastain in the 2010 version.
There were also several semi-action moments that were incredibly out of character for Poirot, yet provided no actual excitement to justify the sudden stylistic change. The ending hints at Death on the Nile being the next mystery for this detective masquerading as Poirot to tackle, but Poirot should not be summoned to solve a murder, he simply stumbles upon them whenever he goes on vacation.