Why would anyone do this?
I'd like to see a rational discussion (yeah I know) as to why anyone with an iPhone would want all their commands to be sent to MS (and beyond???).
Cortana might be better than Siri but I wouldn't know coz I have Siri disabled on my company iPhone and I have no inclination to use either tool.
From reports I've read (don't know about the truth of them though) is that Cortana sends everything back to the MS Mothership like search on W10 sends everything to Bing even if it can be answered locally.
I have seen very few Windows Phones in the wild but on the train the other day a woman was using Cortana a lot. The whole car knew about it and the fact that she was trying to book a restaurant for her boyfriends birthday surprise. Why? Now people will know that her pad will be empty for that evening. etc etc etc
My only conclusion is that she was going cold turkey on using Facebook/Twitter.
But hey, what do I know eh?