It's really a pity that one of the best Poirots is marred by the casual anti-semitism of the era. One offhand remark could have been put down to a character's crassness or prejudices, but it comes from many sources.  The most widely adapted Poirots, Nile and Orient Express, are also among Christie's strangest.  Here, the situation is much more straightforward, much closer to Christie's home and heart.  

A crumbling old seaside Victorian home and a circle of young Londoner friends, ricocheting here and there, with shifting loyalties, deep passions, and, of course, just beneath the surface, the cold need for money, and lots of it.  Poirot is nearby when a murder is attempted, so he takes on the difficult matter of preventing the next attempt from succeeding.  The thrill of the chase is ever-present; the urgency of catching the murderer before they succeed (or, after they succeed twice...) is vital.  And Christie plays fair. Everything we need to know is right here in front of us. We just need order, method, and the application of the grey cells to make it work.  This is the nature of the best Poirots.