I finished Seveneves today. I agree that there's obviously a huge difference between the first 2/3 and the last - but how can you tell the second part is bad if

I finished Seveneves today. I agree that there's obviously a huge difference between the first 2/3 and the last - but how can you tell the second part is bad if you only read the first? Personally I think both parts of the story are good. I think that it could possibly have been split into two different books to give the second part a bit more space. As it is now, the second part is a bit rushed, and ends quite suddenly (in classic Neal Stephenson fashion).