If you treat Seveneves as one book, that might annoy you. If you treat it as two books, published at the same time so you don't have to wait for the next one after you've finished the first, then it suddenly makes sense.
And if you're used to Neal's writing style, then you already possess the patience you need with almost every one of his books, because they usually start slow and build up a tremendous momentum over time, until they reach a frantic pace and then they just... stop ;)
Don't get me wrong, I love his books, but I'm all too aware that you simply have to get used to his style and "forgive" him for certain aspects of it. I know I can and do, but I also know people who can't.
That was my problem with Diamond Age. I was left wondering, "Where's the last 100 pages!? Is this an unfinished manuscript?" Cryptonomicon was better balanced at the end, IMO. Snow Crash was OK (given that it is kind of a weird book overall), but similar trend.
Also, if you enjoyed the Shaftoes and Waterhouses of Cryptonomicon, consider putting the Baroque Cycle before Seveneves.
I pretty much gave up Stephenson after I got half way through "Cryptonomicon". (Really enjoyed "Snowcrash" and loved "Diamond Age"). But then I read (half of) it after I'd just finished Singh's "The Code Book".
It just felt like Stephenson's science and drama subtracted from the real-world science and drama the book was inspired by.
My theory was that after "Diamond Age" he couldn't get an editor that dared cut his manuscripts in half any more. But I'm willing to give some of his newer books a chance -- I see they're quite well received by people that seem to like other good books :-)
If you enjoyed "Snow Crash", you might also enjoy (or hate...) Bruce Sterling's "Islands in the Net".
The Baroque Cycle is fantastic and I just finished Seveneves which is really good as well.
I started reading Anathem, which I know is seen as his "seminal work" but it's been a slow start for me: all the made-up vocabulary combined with strange names makes it a very disjointed reading experience.
I read the first chapter of Seveneves back in May, so that one is on the list, as is The Baroque Cycle.