How about they actually get around to releasing it on Windows Phone? I bought a Lumia 735 three weeks ago partly based on advertising on the MS NZ site that said Cortana was available. It's not, and now they've removed that page.
The most annoying thing about that is the "quiet hours" feature is somehow dependent on Cortana, so the phone doesn't do that either.
(Other than that, very nice phone and OS, just hobbled)