I haven't seen Blade Runner, but "Do Androids Dream of Electric Sheep" is the book on which the movie is based. The protagonist's job is to hunt androids that seem very much like humans.
The book is thought provoking right off the bat. At the start, I actually thought that the protagonist was an android himself because he was using a machine to manipulate his emotions. At the very least, the book raises the question of human exceptionalism: if androids are considered different from humans because their emotions are a little different from ours, but human emotions are themselves manipulable by machine, then it seems unjust to treat androids as second class citizens.
The book brings up some issues of life in a dying world (eg, the main world religion in the book is vegetarian because of a karma-like experience of all beings being connected). However, I find "The Road" to be a more compelling exploration of that question.
Like many of Philip K. Dick's novels, there is also a lot in the book that seems like it might be meaningful but that I can't quite figure out.