The magic of crime fiction

I am rediscovering the world of crime fiction--all over again--thanks to Agatha Christie. I don't know what exactly makes her books scintillating but if I had to pinpoint some particular reasons I would say it is the interplay of logic and events, the placement of facts and a very shrewd study of psychology. Intellect and clarity have always been the greatest attractants for me in most facets of life and reading is no exception. Every time I read an Agatha Christie, it is like trying to solve a complex puzzle--I am in the race with the detective, fitting clues together and trying to race him to the finish line. Not that I have won any of these games yet but it just goes to show how skilled Christie is at her craft.
Take "Cat among the pigeons" for instance. The suspects were not very many but the way in which everything was put together in the end was extraordinarily neat. It was made even more attractive by the fact that there was a faint suspicion on the secretary all the time but there was no evidence in my mind to back it up--the story was complete only when Christie pieced it together in her final chapter.
"Appointment with Death" had a different approach altogether--everyone was a possible suspect! The killer turned out to be someone completely unrelated in the end and to my mind that made the story lose some of its thrill but I could not question the motive or opportunity.
Not all of her books are clean and crisp. "Murder on the Orient Express' was not a very satisfying book for me--things were left hazy and there was no culprit identified at the end. It was good story but not befitting the genre of crime fiction.
I am currently reading "Funerals are fatal". So far the story has not picked up a great deal in pace but I am sure when it does, it will fly!