Note: Will (maybe) comeback to this in more detail.
I had this brief conversation the other day with someone who complained about too much side scrolling using Windows 8; he said that iOS was a more intuitive/easier experience. Now I thought he meant gestures (and so put my nose in it) and said Metro only has four gestures. He responded by saying it was about having to navigate within the app (scrolling).
I brought up that boring (I’m not Bill Cosby people) story to say this; the argument about the intuitiveness/complexity of Metro as opposed to iOS is a moot point. Both take different approaches to how people directly interact with the device.
(Now the part where the non-designer schools the people)
While Metro and iOS are touch systems, they differ in the way they go about it. Both require direct interaction by the user; but Metro relies on it more than iOS. iOS still uses elements of the desktop in its design; the controls are there siting on top of the app. Metro’s interpretation of direct interaction is based on the Microsoft Surface (aka the a** table); here they is no easy way to stick controls and menus so the interface is designed for almost literal hands on interaction. Metro makes use of semantic zoom (the ability see an overview of information) to scroll over large areas of information. The whole design kind of mimics reading a scroll. The difference can be seen in the design of each device; iPads stress the portrait position a bit more than Windows 8 which stresses landscape orientation. This is in part because (my theory) that Microsoft assumes many people will use keyboards and docks. Apple however thinks users will be using the device as mostly a tablet (which may be why their keyboard accessory has the iPad in portrait when docked). If you are use to one, the other will feel unnatural, because in part you are “moving” with the information as opposed to pressing a button and the info moving over to the side.
And that, boys and girls, is the difference between iOS and Metro