History remembers Scanners for one specific scene, and that scene happens to come about 10 minutes into the movie. The question then is what fills more than an hour of the movie after you've gotten what you came for. Hopefully the answer you're looking for is a bizarre thriller with a lot of shots of people contorting their faces and a lead who delivers every line in the most dead pan tone possible.
The scanners are a small percentage of the population who exhibit a genetic mutation that makes them psychic. These people are often maladjusted to society because they cannot cope with hearing everyone's thoughts. Dr. Paul Ruth (Patrick McGoohan), has been studying scanners for decades though and has been teaching them to control their powers. Ruth has been working with the government to explore the scanners' capabilities for combat and espionage, but things are soon interrupted by a scanner uprising lead by one of his former students, Darryl Revok (Michael Ironside). Needing the assistance of a scanner who Revok hasn't been able to get to, Ruth brings in Cameron Vale (Stephen Lack) off the street and teaches him how to fight Revok.
This is a David Cronenberg movie, and it's done in his typical style. Body horror, philosophy, car crashes and strange performances are all mangled together into a throbbing mess that you just have to look at. Tone-wise, I wouldn't even say Scanners is a horror movie, but you'll definitely see some horrific images. There is a reason many people only remember the beginning of this movie though. It isn't the sexy kind of sci-fi. The plot involves bureaucracy, Cameron is almost always emotionless to convey that he's spent his life on the outside of civilization and most of the action takes place inside character's heads. The film never pulls off anything that matches the spectacle of its introduction, so it might seem boring if that's what you're expecting the whole movie to be like. If you just want something weird and cerebral though, I think you'll have a good time with Scanners.