Blade Runner is a visually stylish film with a really great story. It has that bit of mystery, romance and action to round it out and offers anyone, with even a vague liking of sci-fi, something to enjoy.
That it’s essentially a detective story is one of its great strengths. That Harrison Ford plays the detective is one of the others; a perfect actor for the role thing. But then, the rest of the cast is pretty good too.
And for the record, I’m talking about the original theatrical release here, not the director’s cut (which I kind of hate both for its pacing and for, arguably, starting the director’s cut trend).