Superintelligence is a fearmongering book with little internal consistency. It makes quite a few leaps of logic, and seems to be more about dreaming up doomsday scenarios than thinking about them. About the only realistic scenario is "a super AI controlled by a hostile nation"; all the stuff about turning the Earth into paperclips (or whatever) is just nonsense. It's a "pop science" book.

I did like the 'history' bit at the start, where it mentions the frustrations AI researchers have - every time they reach a goal, it's then labelled "Not AI", and the definition of AI then becomes more complex.