I have been building my Agatha collection over the years and I there are so many I haven't read yet. Fortunately I do have this one. I'm glad you liked it so much. I'll give it a go myself sometime in the future!
I really think that this is a top tier Christie - up there with And Then There Were None, Roger Ackroyd and Orient Express. One of the things that Christie definitely doesn't get enough credit for is how innovative and experimental some of her plots/narratives are and this one is particularly good. It also has some of the best characterizations in the Christie-verse.
I hope you enjoy it, too!