If you're into Cortana, but don't want to make the plunge to a Windows Phone, Microsoft has dedicated themselves to pushing out their software to Apple and Android devices as well (sometimes before their own platforms). Cortana isn't done yet but all means, but it makes at least as good of a digital assistant as Siri - and you get to think of all the fond memories playing Halo to boot.
The Cortana app can do most of the things Cortana does on your PC or on a Windows phone. With the app, you can manage your hectic lifestyle by setting and getting reminders, searching the web on-the-go, tracking important information such as flight details as well as starting and completing tasks across all of your devices.
Source: Windows Blog