I haven't finished it yet, I'm a bit less than halfway through. I did go back and reread Pattern Recognition in preparation earlier this week because I had read that they shared at least one character. It goes a touch deeper than that. Not that you'd need to read PR to understand Spook Country but there's been one clear reference that says the events of PR precede SC.
Gibson books are often difficult to get into, I personally find it a struggle to establish empathy with the characters. It's worth it to do so but it does take some effort. Spook Country aggravates this because it starts with three different stories and three different POV characters. Initially Gibson rotates with each chapter being a different POV, so there are THREE characters to struggle with identifying.
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