In the 'future' of 2019, humanity has handed most of its dangerous, dirty work into the care of artificial humanoids known as replicants. The latest models of these replicants are distinguishable from humans only via a complex pyschological test. They're also stronger and tougher than we are, but genetically engineered to have a lifespan of only four years.
Because they present a 'danger', replicants are banned from Earth. A special police unit known as 'Blade Runners' is set up to hunt and 'retire' them when they do. Our film begins when group of replicants go rogue and come here in search of the man who masterminded their creation, then kill the first Blade Runner assigned to find them. The hunt then falls to Deckard, who is forcibly drafted back into a service he'd previously quit for one last job.
I must admit that I've never liked Blade Runner as much as the geek handbook says I am supposed to. I think the first hour is too slow, the romance is unconvincing - and at times just plain icky - and the investigation is (a) powered mostly by luck and the incompetence of the bad guys rather than any special skill on the part of the protagonist and (b) largely a failure in any case.
What the film does have going for it, though, is great visual design and an evocative vision of the then seemingly far-off year of 2019. Watched today, some of the details are delightfully anachronistic - apparently we can have flying cars and off-world colonies, but the idea that we might have a phone we can carry in our pockets is just craaaazy - but it looks great, and it's refreshingly ethnically and culturally diverse. We don't often see films that have the courage to imagine a future that really feels different to the time it was made. Normally it's just "today's culture, but with new tech". It also benefits from a fine performance by Rutger Hauer as the leader of the replicants.
Blade Runner is worth seeing for the visuals and the cultural imagination it shows. I think it's certainly worth seeing for those factors alone, but it's most definitely a flawed film in my eyes.
(Note: There are a lot of versions of this film out there, so to be clear, this review is of the 'final cut', which differs from the original theatrical release mainly in that eliminates that version's explanatory voice overs and tacked on deus ex machina happy ending. There are other chances, but you probably won't notice.)