I find myself intensely interested in understanding the mechanisms behind intelligence, but also incredibly ambivalent about the likely results, making it impossible for me to work in the field (hence, I don't). I wonder if other people feel the same way.
It seems to me that AI will displace not just the drudge work that we dislike, but also much of what makes us value ourselves as humans distinct from animals. It will create complex, rights-possessing entities for us to deal with, when we already can't deal with each other.
Some, like Kurzweil, believe AI will facilitate scientific advances allowing us to colonize the universe. This is an irrational belief because it depends on the underlying laws of the universe, and those laws don't derive from our desire to spread through space.
Kurzweil also believes that once there is an AI, we will all want to merge with it in some way. The first big question here is why it would want to merge with us. Another is whether that would mean the ultimate end of the race, given that our race evolved by definition for survival on this planet, whereas an AI, however brilliant, did not.
While AIs will eventually get clever, the early versions will be dull conversationalists. We'll go through a phase where people spend a lot of time interacting with dull AIs. People tend to become like the people they interact with, so it will cause a cultural downswing. You can already see it among people who spend more time interacting with video game NPCs than their peers. Their conversation is full of repetitive gaming memes rather than novel insights.