As an hourly user of Cortana on my Lumia 640 XL, and on my Windows 10 TP 10240, I can tell you this; she blows Siri out of the water on SO many levels, and she is so cute, polite, witty and affable.
"Set alarm 4 mins" for brewing my coffee
"What's the weather?" when I wake up
"Open <insert_app_name>" this is often hilarious, as you see on the phone screen the misinterpreted words of what she THOUGHT you said, and as you read that, it's phonetically almost identical to what you ACTUALLY said, and she ALWAYS opens the right app, even when the misinterpreted words of your command are on screen; BRILLIANT!
"Turn on quiet hours" (shut up phone, I am busy until further notice) - SO handy.
"Turn off Wifi" / "Turn off WiFi" - she confirms, as always, and it happens
IMMEDIATELY
"Flight mode on" / "Flight mode off" (or phrases very similar also work) - and yes - she can turn flight mode AND WiFi back on, WITHOUT A DATA CONNECTION (pah, let's see Siri do that!)
[Hold down search key / say
"Hey Cortana" on supported models]:
"Text <insert_name>" - she asks what you want to say, and so on. IF you have enabled it, she will read out all texts when they come in - I can have a complete, hassle-free sms converation with my phone IN MY POCKET - so useful when cooking, "indisposed" etc.
Cortana on Windows 10 is not *quite* perfect yet, but is still a supremely stellar, very useful assistant.
Cortana, if I met a girl with a voice like yours (UK English voice) I would propose; she has
exceptional British elocution, a very nice, clear and polite tone of voice - SO CUTE
