I read this first when I was about 19. I remember being confused a lot by it and didn't really understand what was going on.
I want to add to this and say that Gibson's prose is incredibly light (it's not labourious, and convoluted sentences using words particular to this novel just roll off the page), but simultaenously powerful and paced so well, an example:
"Cold steel ice odor. Ice caresses his spine.
Lost, so small amid that dark, hands grown col, body image fading down corridors of television sky.
Then black fire found the branching tributaries of the nerves, pain beyond anything to which the name of pain is given..."
"The landscape of the northern Sprawl woke confused memories of childhood for Case, dead grass tufting the cracks in a canted slab of freeway concrete.
The train began to decelerate ten kilometers from the airport. Case watched the sun rise on the landscape of childhood, on broken slag and the rusted shells of refineries."
Great book. I read it in high school and, as you say, it took a second reading whilst at uni to really sink in.
It's got a great first line - "The sky above the port was the colour of television, tuned to a dead channel." - although I do wonder what kids nowadays, raised on digital TV, would make of that given that TVs don't really show static anymore.