The edge.org annual question was on this exact topic.

If anyone wants a range of informed opinion on this topic, check out these 180+ (and counting) responses here:

http://edge.org/responses/what-do-you-think-about-machines-that-think

Here's a sample quote from Sam Harris's response:

"imagine, for instance, that we build a computer that is no more intelligent than the average team of researchers at Stanford or MIT—but, because it functions on a digital timescale, it runs a million times faster than the minds that built it. Set it humming for a week, and it would perform 20,000 years of human-level intellectual work. What are the chances that such an entity would remain content to take direction from us? And how could we confidently predict the thoughts and actions of an autonomous agent that sees more deeply into the past, present, and future than we do?"