I think William Gibson is probably the best pure writer that I have read for years. I don't think, on the other hand, that his fiction is the best that SF has produced--but his deliverance of the stories is his strong point. His prose has been polished to the point that it sparkles and contains more than a good deal of poetry. Not only is his language poetic, but also are his images, especially his depiction of cyberspace with all its colorful towers of data.
As far as Gibson's fiction is concerned it is always interesting, often relevant, and on occasion cathartic. Most of his stories seem to take on the same sort of tone, that stemming from the "hard-boiled" tradition. Stories like "Johnny Mnemonic" and "Burning Chrome" best exemplify this particular brand of story. But Gibson also pulls a few surprizes out of his hat and delivers stories that are highly experimental and center around character study rather than high-tempo, action-packed adventure stories. "The Winter Market" in particular struck me as especially brilliant. His focus in the story was not the neat gadgetry that was represented by the "exoskeleton" worn by one of the characters, it was how this shaped this character and effected her life. But Gibson doesn't stop there, he gives us a cast of strong characters and plenty of interaction between them. And this is what really made the story interesting for me. The sf elements are there, but the story has a great deal of universality in its portrayol of real people in situations we can relate to.
I also thought that "Hinterlands" and "The Gernsback Continuum" were very interesting stories. "Hinterlands", like "The Winter Market", tells a real character oriented story, and "The Gernsback Continuum" is unlike any other story I've ever read. All of Gibson's stories are well written, but these stories in particular established his reputation in my mind.