A lot of positives, but ultimately not very good.

Rating: 3/10 (11 July 2016)

As a piece of visual art, Blade Runner is very impressive.
The problem is that it never gets around to telling a good story. The story that is there is extremely drawn out, and depressing. It is a slow, boring, melodramatic movie that has very little humanity (which is part of the premise), and nothing for the viewer to care about. It's a pretentious, navel-gazing art house film dressed up as a sci-fi/film noir thriller.
Vangelis's score is sometimes praised, but really not very good. Aside from a few good moments, he's mostly playing weak jazz and blues on synthesizers, or somber piano music.
As science fiction, it's kind of interesting in retrospect to see what predictions it got right, and what it got wrong. In Blade Runner's 2019, smartphones and flat screen TVs have not been invented, but androids and flying cars have.
The Terminator, which came out two years later and had a similar (but crucially different) concept, is a much better movie on almost every front, both as a story and as science fiction, although it had a smaller budget and less impressive visuals.
It's not hard to see why Blade Runner flopped at the box office, despite the pedigree it had. Word of mouth could not have been good. The fact that it's been resurrected in critical estimation is entirely about the visual imagery it created, which was, to be fair, mind-blowing for the time and extremely influential on later films. But that shouldn't mislead people into thinking it was a good movie. It wasn't. Its rating on this site is way, way too high. Be warned.
*POSSIBLE SPOILER*
The entire film is basically the examination of a concept: "If robots started to develop emotions, what would that be like?". That's it. It just dwells on that question in excruciating, overwrought, detail for two hours. The plot is paper thin, and an afterthought to the real point of the movie, which seems to have been the visual imagery. The word I used above is how I would sum it up: excruciating. It would probably be a better movie if you watched it with the sound off, and some electronic music playing.