When I try the Bing Maps Preview app on my surface tablet, my fingers need to be ~2 inches apart before a zoom gesture will begin to register. This creates a highly uncomfortable experience where I begin a pinch-to-zoom gesture with fingers together, and upon spreading them nothing happens. It's only when my fingers are reaching mid-to-full extension that the map begins zooming.
On a large touchscreen this finger distance issues amplifies to a huge problem, since I can't stretch my fingers wide enough to get any kind of substantial zoom. *ouch!*
Initially, I suspected the app was just non-responsive, but this appears not to be the case.