It will integrate to a degree but not completely. You can MAKE calls with Alexa, but you can't receive calls.....at this time. If you have an Apple Music Subscription, it can easily be your default music service. It will incorporate your Apple iPhone calendar, so you can set appointments via voice and it will appear on your calendar. She will read your text messages, but she can't send them via iOS. You can send an email though and she can read back your emails as well.
Hope this helps!