This is the first Agatha Christie novel I've ever read and I loved it - I'm amazed how she manages to introduce the reader to so many new characters and build a suspenseful storyline in just 200 pages. To a large part, the book consists of conversations between Poirot and the train passengers while the detective mostly holds back his own thoughts of what he thinks happend. This invites the reader to form his own theories and follow along with the investigation (and I loved it).
However, I was a bit disappointed by the ending. Although it was surprising, the absurdity made it unsatisfying.