In general, Cortana did pretty well with my queries. Requests like "What's the best Chinese restaurant near here?" produced a list of top-rated restaurants on Yelp, organized by proximity and shown on an accompanying map. (A similar request for restaurants serving jambalaya didn't work, however.) A follow-up request displayed the traffic.
Cortana addressed factual requests well, including the heights of the Eiffel Tower and Mt. Everest. Asking "who is the secretary general of the United Nations?" returned a Bing query, with Ban Ki-moon correctly called out. But asking how long it took to fly from San Francisco to Seattle (a query Google Now failed to answer, but Wolfram Alpha did) generated an unproductive Bing search. Asking it to "play YouTube cat videos" also brought up a Bing page, although with the correct results.
Both Google Now and Cortana "geofence" requests. If you ask either digital assistant to remind you to buy eggs at the supermarket, it will search for a list of available supermarkets near you. Google Now knows the market I shop at, although granted, I've used it for a much longer period.
But in the keynote presentation, one Cortana feature stood out: Microsoft's Joe Belfiore told Cortana to remind him to ask his sister about her cat. Knowing who you're talking to is a feature Google Now doesn't have, yet.
What Cortana does is put Microsoft and Google neck-and-neck in the race to know more about you, and provide you with useful information. Will they go too far, and cross the so-called "creepy line" in a bid to one-up the other? It's a valid concern, and one that bears watching.
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