Don't get hung up on the organ harvesting
It seems like most people are so turned off by the premise that they are unable to examine the story beyond this aspect. It's rather ironic.
I was able to find a book review that touches on the deeper meaning of the story as I'm too lazy to write it all myself :)
http://www.telegraph.co.uk/culture/books/3638242/A-sinister-harvest.html
I'll quote the concluding paragraph:
Gradually, it dawns on the reader that Never Let Me Go is a parable about mortality. The horribly indoctrinated voices of the Hailsham students who tell each other pathetic little stories to ward off the grisly truth about the future - they belong to us; we've been told that we're all going to die, but we've not really understood.
I think if the movie is approached with this understanding it becomes far more meaningful. I'd certainly be willing to elaborate if there is any interest in this discussion. share