About Cortana... I find it to be somewhat of a parlor trick and not super useful. I mean I used it for a few days then it got old because the vast majority of results are simply web searches.
For instance, once it can answer obscure yet simple questions without doing a web search, it would become more useful. An example is: "How many toes does a dog have?"
All non-web searches are simply canned responses. It can't even read back: "What is five times ten?". At least it shows you the result above the web searches.
Also sometimes I have great problems with voice recognition. I simply cannot get it to recognize "What does the bird say?". It always recognizes it as "What does the birthdays?" no matter how much I try to enunciate the "d".
I have the Sync infotainment system in my car (from MS), and my phone connects automatically when I get into the car, so all phone calls etc go over the in-car mic and speakers. So once while sitting in the car (parked), I tried to do a search but it absolutely could not do any voice recognition. It seems the car mic doesn't work well with it, although phone calls are very clear to the other parties so it has to be a Cortana issue.
Off-topic... Why is it that my FM radio can show me artist/song info, but my Bluetooth connected MS WP connected to my MS infotainment system cannot show any artist/song info whatsoever? All it can do is simple transport controls. When it works that is. Sometimes it just doesn't want to play anything and I need to restart the phone to get it to work. This stuff should work seamlessly by now, yet still feels like betaware.