That's not exactly a substititve counterpoint.
I use Google Now on my iPad and GS4 and beyond the push notifications and useless wake command, this OS integration doesn't manifest in any meaningful way.
The android version has some personal digital assistant functions that work as a Siri alternative sure, but when I'm on iOS I use Siri so that doesn't matter. Plus Siri does a better job. When I say call or text "my wife" it knows who I mean because Siri has some contextual comprehension. Google now does not.
Google now can call your wife and on iOS it won't do that .
Why are you not understanding this simple difference