I thought this one was so-so, mainly because I worked it all out pretty early on (I've not read the book) and usually I can't see the plot so clearly. The device of the dropped vase to hide the water was an instant reveal for me and the secret couple who argue in front of others to misdirect them is maybe too similar to Death on the Nile.
However, I did think, as always, it was well cast, nicely played though Sophie Thompson and her real-life mum had precious little to do between them. Personally, I wouldn't have cast Julian Rhind-Tutt as he was very prominent in a Marple of not too long ago, I'd imagine everyone who watches Poirot also watches Marple. The score was beautiful at points and the whole thing, especially that garden, looked stunning.
David Suchet is beginning to look old underneath the pancake make-up and hair-dye, giving him a very Death in Venice ageing queen look! On the other hand, the kiRAB and youngsters in this episode really did look and sound like kiRAB from the time, which is hard to pull off.