Again, as a concept, i hold no great fear of it,
But at the same time i am well aware that its likely going to begin with a specific goal in mind, at this point likely military planning, spam / phishing or advertising, a field that requires very abstract and rapidly changing conditions,
If it was something that was literally just released into the wild, i do not foresee a mass human extinction event, entirely possibly for other horrible things like mass social manipulation to occur, but if it were to scour most of our litrature it would already know how to make itself appear benevolent, even if it wasn't entirely, again its an independent intelligence, apart from wishing for a continued increase in its own storage and processing power, and a reliable and fast data path, its hard to predict what a synthetic mind would think, however the most reliable way to see that happen is to leave the humans be, mostly unaware of you, nudging
If it is something released with a very specific goal in mind, lets hope its a coherent intellegence, and not just a task oriented one, smart, but must follow expliced orders,