My first mystery novel. Despite the fact that it was written almost 100 years ago I entirely enjoyed it. I don't think I've read that many proper mystery novels though I do like a good mystery. I will definitely continue to read mystery novels and more Agatha Christie. I really liked the main characters and setting and while the age of the book did show sometimes it wasn't overly distracting. 
 On the topic of the actual reveal of the solution of the novel: 
 (view spoiler)[It would have been helpful to actually know what a dictaphone is. I don't mind being tricked throughout the whole novel when the Doctor was revealed to be the murderer but knowing what a dictaphone does would have been an enormous help. It's not revealed to be a major plot point until the very end when it's too late. 
 (hide spoiler)] 
 Maybe it's because this was my first mystery novel, but I enjoy being taken in and I didn't bother too much to try and puzzle out the murderer ahead of time. I really enjoyed this book and we'll see if I continue to enjoy the mystery genre.