Perhaps you've covered this, but what exactly does "friendly" mean? Do what I say? Including enslave my fellow humans?

Make me do what I should? Including forcing me to exercise regularly, and preventing me from eating what I want?

Support human improvement? Including reengineering my body/mind into whatever I want?

Make me happy? Including just inventing a really great drug?

I don't know what I want AI to do for me, so I have no idea how you would build a system that knows. And no idea how to resolve differences in opinion between myself and other humans.