I have my Cortana on. I have a lot vested into the Microsoft ecosystem, so it's a good pairing. What I find nice are some things it does automatically. My calender gets filled out nicely with package deliveries and the like. It also fills out emails for me when they are nearly identical without me going to copy and paste or open a draft. Just hey you are sending an email to this person, here is 80% of the email filled out.