There's a more recent article in the New Yorker that follows Mr. Bostrom around a bit and is a good general read:
http://www.newyorker.com/magazine/2015/11/23/doomsday-invent...
So the most influential AI doomsayer on the planet has been writing about artificial minds for a couple of decades, without even knowing enough to get a computer to say "Hello, world"? OK...