Honestly hated Seveneves, it marked the point where I stopped reading Stephenson. With that said, I agree the final part of the book is the most interesting by far.
Personally I thought Seveneves was pretty good ... the most recent Neal Stephenson novel I read was "The Rise and Fall of D.O.D.O." and I loved it. As with Snowcrash, it'd make an awesome movie (if done right)!
I feel like the guy has skill, but it’s unreliable as to whether he’ll employ it, get preachy or wander off entirely.