These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Seinfeld Is Unfunny: Every other cyberpunk work done after Neuromancer was released used it as a base, even by copying the terms at times. Combined with Science Marches On and the rise of the Internet, it can make some of the book's elements feel rather dated to the modern reader.
This was even the case at the time; Gibson notes in one introduction that he was quite dejected when Blade Runner was released while he was still working on the book, as suddenly it would look like he was ripping off the film's aesthetics.
Tear Jerker: when Corto-Armitage gets spaced, the usually relatively stoic Case starts crying. Admittedly, he's crying because he wants to keep his ability to stay in the Matrix, not because he liked Armitage, but still, it's kind of depressing seeing him that broken. It doesn't last long, though.
Technology Marches On: Gibson wrote most of his early works on a typewriter. A copy of Neuromancer printed in 1994 includes an afterword by the author on that subject. Included in the afterword is a reminder to his modern readers that the typewriter was the high-tech whizbang of the day. In 1981, the hottest computer on the mass market was the Apple II (not even the IIe, yet), and that cost a bundle.
Case starts out trying to sell "three megabytes of hot RAM" in a world where Brain Computer Interfaces are commonplace. At the time the novel was written, the Apple II came with 64 kilobytes of RAM. It is possible that it was the contents of the RAM that was really important, but this possibility isn't even suggested until much later in the book, and even then would only make slightly more sense to a modern audience.
The book famously begins by likening the colour of the sky to that of a television tuned to a dead station. This originally conveyed a gray, dreary day, the colour of analogue static; nowadays, most TV sets default, ironically, to a blue screen when there isn't a channel or anything to display.
This was referenced in Neil Gaiman's novel Neverwhere, which opens with, "The sky was the perfect blue of a television, turned to a dead channel."
One scene takes place in an arcade, which have gone the way of the dodo with the rise of home video game consoles.
In Japan, however, video arcades are still common.
VoIP apparently doesn't exist, and the only way to call someone from an airport is a bank of pay phones.
More recent editions include an introduction by Gibson apologizing for his failure to foresee the rise in cellular technology.
Ironically, as Augmented Reality becomes closer to fruition, the less likely it is that it will look anything like Gibson's vision of cyberspace. Most computers are also much smaller and lighter than Case's Hosaka (although possibly not more powerful yet).