I suppose I will have to wait and see the data, once there are enough self-driving cars on the road that are simultaneously sharing with road with human operators in order to convince me that accident rates are decreasing.
At this stage, I see it as a danger, because I believe many (not all) users of self-driving cars will see the current technology as essentially a justification to divert their attention from the road in order to give their attention to something else, and this will ultimately cause more injuries and deaths, at least in the near-term.