John Gruber’s excellent iPhone 5 review highlights the challenges of a bigger display. Unlike other reviews, Gruber has honed in on the biggest challenge many iPhone users will have when it comes to using the new iPhones.

The bigger display is a total win while using the iPhone 5 two-handed. But navigating the full screen while holding the iPhone in one hand is worse, for exactly the one reason why, even one year ago, I did not expect Apple ever to increase the size of the iPhone display: my thumb no longer easily reaches from corner to corner. (My hands are at least somewhat larger than average. Perhaps, counter-intuitively, this issue will not be noticed by the smaller-handed, whose thumbs don’t easily stretch from corner to corner even on a 3.5-inch iPhone display.) Consider the windshield wipers on a car, and how, because they swing in a radial arc, they can’t reach the passenger-side top corner. Using the iPhone 5 is like that.