Ustinov's second outing as Poirot again features an all-star cast in an exotic island off the Albanian coast (actually it was shot in Majorca, Spain), and while the murder is a quite clever scheme (a trademark of the Poirot adventures) it pales compared to the film classic that was "Death on the Nile" (but proves better than the subsequent Poirot movies like "Appointment with Death" and "Dead Man's Folly").
Ustinov is perfectly cast as the clever, fiery and rather morbidly humoured Belgian detective with scenes like his 'swimming sequence' proving good fun. Emma Peel herself - Miss Diana Rigg is spectacular as the vain stunner actress and does some great banter with her ex-rival turned hotelier Maggie Smith as the claws come out.
Roddy McDowall, James Mason, etc. all make fun suspects though the actors are slightly boxed in by a limited script which never lets them explore their full potential (they do their best with what's available).
It does succeed in terms of plot, with the mystery made quite interesting by the fact that everyone seems to have an alibi that supports one another. Christie's mysteries always have trouble adapting to the big screen, and while this is just a 'good film' its certainly fun for those who get a kick out of elaborate plots and trying to figure out 'whodunnit'.