As someone on Peter Watts' own site is quoted, "Whenever I find my will to live becoming too strong, I read Peter Watts." Reader beware.
I re-read it just recently. This book fundamentally shifted my perspective on my own humanity, and maybe not in a good way. But it did a really good job! I think it took me a few reads to really get a handle on what was happening in the story and that only made the hammer blows of its conclusion stronger.
Has a permanent space on my shelf, except my copy keeps walking out of my house because I lend it out so much.
The author has started giving away this book, available here for free on his own site: www.rifters.com/real/Blindsight.htm
But you might want to consider donating: www.rifters.com/real/donation.htm
Once you've read the book, check out this gorgeous fan-made film: blindsight.space/