A friend just loaned me a massive (852 pp) sci-fi book by Neal Stephenson. I am sorry to say I had never heard of him. i anyone here familiar with this writer? Critical judgments?

Which book did you get?  Some of his books are wonderful, others I feel if I'm being drowned in the wordage.  If it is Anathem, bear with the world building because it's worth it. 

The book I am working on it titled seveneves. I can figure out already what you mean by being drowned in wordage. I don't reuire a book to gallop along as most of today's readers do, but it moves at the speed of a lava flow.

I tried to like Anathem, but no go for me.  Pretentious without substance.  I even bought the unabridged audio thinking it would help me to figure out why this is one of my brother's favorite books.  Not happening for me.  I have a copy I never posted if you would like it, John.

I think Snow Crash is one of his most accessible and popular titles.