To be honest I wasn't expecting much of this - I only bought it when I spotted it in the charity bookshop, not exactly a must read. There are plenty of original Christies that I haven't read and could if I really wanted to read that kind of thing. So the fact that I quite enjoyed it probably stems from the fact that my expectations were pretty low to start with.
It was a good idea to give Poirot a new sidekick-narrator (I presume, he has several different ones as well as Hastings in the original books). Though perhaps it wasn't such a good idea to make him quite so dim. I was waiting for him to suddenly twist something and spot something that Poirot hadn't done, thereby making his presence in the book useful, but it never happened. He was supposed to be a young up-and-coming Scotland Yard detective but I could never figure out why that was.
The plot was pretty preposterous but I was willing to go along with it, Christie did preposterous pretty well herself. The book just felt overlong compared with my memories of the originals which were paperbacks to be thrown off on a train journey, not hours and hours of convoluted complications. The characters felt pretty much like Christie's though, I didn't feel Poirot had been dragged too far into the twenty-first century.
In the end, it was okay, nothing special, and given that there can't be that many people who have read all the original Christies and still hanker for more whilst not wanting to re-read, this really isn't any more than an extended advert by Christie's estate for all her other books.
This was a hardback.