I've been using an iPhone since 2007 and I have to agree with the argument that typing on iOS is more cumbersome than it is on Android, and I've had a mere week of testing android on the nexus 4. Now I'm going back I my old iPhone, but really, Androi clearly wins when it comes to writing. First, there's the swipe feature which isn't faster than typing two handed on an iPhone, but is much more convenient to use one handed. Second, the android keyboard's suggestions are far more accurate in my native tongue, German. When typing in English, however, the iPhone's auto-correction works as good as Android's. (At least in my experience). Also, the Android feature that let's you add unknown words to your dictionary is more convenient than on the iPhone. I know, it's supposed to learn and adapt to the user but that doesn't always seem to work (at least not for me and particularly not in German).
Still, typing is not everything you do on a smartphone and for me, the iphone's simplicity is still superior to Android.