In terms of system responsiveness, it is good, but not “groundbreaking” when compared to other fast Android handsets. I think that this is mainly an Android “thing”, so there’s not much that Samsung can do about this. Android 4.0 improved the UI responsiveness by quite a bit, but in my opinion, iOS and Windows Phone are still more responsive to user input.
Samsung Galaxy S3 Preview | Ubergizmo

WP on a dual core S4 will be a monster