I couldn't read this book fast enough! After the ups and downs of the first two books you're sorta battered and depressed by this point, and there are definitely still some sad points remaining - and definitely not a happy ending - but it leaves you with some good reflections on humanity, life, and the universe.
It moves along pretty quickly. Even when it's depressing it doesn't make you want to put it down - rather you want to see how it comes out of it.
SPOILER ALERT
Man, first the solar system gets destroyed - along with the earth itself - then when you think there's some closure coming, that gets dashed - and ultimately the entire universe ends. Geez.
There are some moments where you just feel empty and hopeless.
Screw you, Sophon! Man I hated here.