Sure, the CGI is distracting, the cast is a mix of flat and overused or charismatic and underused, and the mystery is eminently guessable from the first few scenes, but…
…well, there is no “but”. Much as I like Branagh, his Poirot is at his best in the opening flashback before being largely set aside until it comes time to start throwing around accusations in the final act.
Honestly, I worked out the guilty before the murder had even taken place, and was only briefly diverted from my confidence by thinking maybe there was a meta-twist that I wasn’t considering. Solving the mystery early isn’t in itself problematic—it’s arguably the point of a mystery thriller—but unfortunately there isn’t any real sort of tension or curiosity drawn out.
Passable light entertainment, but there are far, far better whodunnits out there.