Read Naked Lunch by Burroughs, then read Neuromancer. Then read The Ticket That Exploded by Burroughs.

Gibson has mentioned he was greatly influenced by the beats (Burroughs is sometimes called the godfather of the beats) and it very much shows. Somewhere in the 80s people picked up on Orwell's style and encouraged everyone to eschew anything that wasn't short sentences describing physical characteristics.

I don't know if Gibson was trying to make a "difficult to read" text, but his influences were pretty clear about how they cared more about the immediacy of emotional impact than clear prose.