Please note: I don't review to provide synopses, I review to share a purely visceral reaction to books and perhaps answer some of the questions I ask when I'm contemplating investing time and money into a book.
When I started this book, I was using an AG2 running MoonReader. My pageview wasn't setup to include page or screen counts. I had no idea this book comes in at over 1000 pages (according to Amazon's count), and to be honest if I'dve known that I probably would've DNF'd at 10%. I didn't figure out it was so long until around (virtual) page 250 and I thought to myself, "This has been going on for a long time, and yet more complications are being added and nothing is getting resolved - how is this going to get wrapped up?" By that time I'd become invested in a couple of the characters, and my ego decided to make this into some sort of titanic battle of my will to continue vs. Mr. Stephenson's verbosity.
My ego won. Despite a catastrophe with my AG2 with 100 screens left to go, I finished the book. Do I feel edified? No. Entertained? Meh; there was some great parts and there were a lot of very long stretches that needed an editor's red swipe. Accomplished? You betcha.
There are 4 different 250 page thrillers in this book. Any one of them could stand alone and do well with the techno/thriller/pre-cyberpunk crowd that Neil writes for. Smashing the four of these together was ambitious, and I feel like I understand why Mr. Stephenson felt like this book needed so many storylines, but I don't know if it really needed to be this complicated to say what he was trying to say. I value brevity and succinctness and Reamde had very little of either. Choosing a single plot thread, then backing it up with hints and wisps from the other plotlines would have made for a much stronger product in this reader's opinion. The fact is, some of the plotlines were weak and needed inordinate amounts of filler to shore them up and try to get them stand on their own.
And therein lies the crux of my problem with this book. There is way too much filler. At least 250 pages worth of unnecessary asides and descriptions could be wiped from the book with no detriment to the plot whatsoever. Here's a short list from the top of my head of some descriptive passages that went on for several screens without any advancement of the plot:
Setting up a TOR node on a shared PC
Lore regarding grizzly bears' ability to smell
Building a secured cell inside an RV
Querying a database
These would all be great if I were looking for documentation on any of these topics, but I wasn't. And that's just what I recalled with a few seconds of effort; the whole book is peppered with a level of detail that is wholly unnecessary. I was trying to enjoy a story about an unlikely band of characters thrown together by fate and trying to outsmart a caricature of the 21st Century Boogeyman: A dark skinned jihadist who looks and talks just like middle class white folks.
To make these wildly different characters get vested in the same outcome required some serious shenanigans on behalf of the writer. The terms "contrived", "outlandish" and "almost ridiculous" come to mind. Of course the world is full of amazing coincidences and near misses; but relying on whole consecutive steps of unliklihoods to drive a plot feels more appropriate to a comedy of errors than a techno thriller. The characters in this book move through a bubble where normal statistics don't apply. It was fun for the first few hundred pages, then it became tiresome, and by the end it was just another annoyance I had to put up with to get to to the finish line.
The characters themselves don't feel like they're "getting lucky", but neither do comic book heroes. All our main characters are interesting in their own right, and voiced well, but there's a very strong sense the characters get moved around and motivated according to the outline the author sketched before writing the book, rather than organically going where they need to go. Characterization, never one of Mr. Stephenson's strong points, isn't weaker in this book than in the others I've read but it feels like it's worse because it goes on for so long.
I liked the different settings, and the scene building was handled very well. I felt like I had a sense of place in all the locations. The settings were "voiced" like a character, and lent their own flavor to the parts of the story they related to. I wouldn't say the scene building was vivid (except where descriptions went on too long) but it was very evocative. A good chunk of action happens in Seattle, and having lived there for a number of years I can say that he captured the feel of the town and the Cascade Mountains perfectly. I can only assume he was as accurate with the other settings.
The finale, like the rest of the book, was way too wordy and took way too long to wrap up. I wanted to hurry up and finish it just to find out who pulled the trigger that killed the Big Bad Guy; I was still invested in some of the characters but I had no expectations that they would suddenly arc in a surprising direction. By the time the final gun battle shapes up, all the characters are finally in place and it felt like it was just a matter of putting words into my eyes until I reached the end of the book.
I'm feeling a difficulty trying to rate this; my enjoyment of the book declined the closer I got to the end. The beginning was everything I expected from this author and I was set to star the heck out of it, but then it just went on way too long without doing anything clever. In a lot of ways, this book is like that guy you work with who's really smart and mildly autistic - it just drones on and on about the minutae of some inane topic despite every cue that you're ready to wrap up the conversation.
 But I don't like poetry - go figure