I've been wondering why Apple chose to make the iPhone 4's screen 3.5-inches when other comparable phones with Android and Windows Phone 7 have larger, more inviting screens. When you first see a phone with a 4-inch or larger screen, it seems like a much better experience. I thought it was a technical decision, and it could be, but since switching to an Android phone – a Samsung Galaxy S II, the “best Android phone you can buy, anywhere” – 15 days ago, I have realized another huge downside of larger screens: when holding the phone with one hand, I can't reach the other side of the screen with my thumb.
Touching the upper right corner of the screen on the Galaxy S II using one hand, with its 4.27-inch screen, while you're walking down the street looking at Google Maps, is extremely difficult and frustrating. I pulled out my iPhone 4 to do a quick test, and it turns out that when you hold the iPhone in your left hand and articulate your thumb, you can reach almost exactly to the other side of the screen. This means it's easy to touch any area of the screen while holding the phone in one hand, with your thumb. It is almost impossible to do this on the Galaxy S II.
This is an example of one of those design decisions that you don't usually notice until you see someone doing it wrong. It's one of the things that makes Apple products Apple products.
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