Dude, Blade Runner is just...indescribably good. But, truth me told, when I first watched it at 15/16, I didn't quite get it myself. It seemed overly dark and hard to follow visually, they scenes had an overly slow and plodding pace, and the plot was extremely basic and unsurprising.
But as my taste in film has seasoned, it's really become one of my favorite movies of all time. Visually, it meshes post-apocolyptic future-sci with a heavily film noir visual style that, arguably, adheres to the principles of the genre even more closely than a lot of legitimate film noir movies from the '40s ever did.
It also utilizes its cinematography to illustrate the finer aspects of its story extremely well. I don't know if it's ever been said, but I certainly think it very much is imbibed with the visual storytelling principles of a lot of silent films - where much of the characters emotions, mechanations, etc. are explained and explored purely through their reactions, facial expressions, and visual metaphors.
I don't think any other movie in the history of film has had a score as definitive and important to the storytelling as Blade Runner's did. The Vangelis' symphony didn't just string together quality melodies, it actually drove the tempo, mood, and execution of the film's story overall.
And the script? Perfectly written. It was the most incredible melding of plot simplicity and character complexity. Despite being little more than a rather vapid detective story, Blade Runner's script had to instill a tremendous amount of backstory, philosophical and more questions, and character emotion and motivation into where dialogue was kept to a minimum, and even when things were said, they never actually confronted the film's subtext head on. That's mastery of writing and filmmaking right there; being able to have a character say one thing - or nothing at all, even - but still have a phenomenal amount of emotion and meaning ring through.