Beyond increasing the phone's height and adding roughly 113,000 pixels, this change allows every page of the home screen to fit an extra row of icons, so you can stick four more apps in places you couldn't stick them before. App folders are similarly expanded. Widescreen movies and TV shows fill the screen instead of displaying letterboxed (or with their sides cut off). When you shoot video with the iPhone 5 camera, you can see the entire frame of what you're shooting without double-tapping to zoom out as on previous models.
Apps, on the other hand, display with black bars around them unless they've been updated to take advantage of the iPhone 5 screen's height. In practice, this isn't a big deal--the black bars are so black as to basically disappear into the rest of the display, especially on the black model. It does mean that the onscreen keyboard is shifted up from where it usually is, which requires a minor adjustment.
Apps that have been updated to support the taller screen appear to have taken one of two approaches. Some just show you more of what you had before: more emails, more tweets, taller webpages. That makes sense for apps that are essentially just lists of things. But other apps can use the greater space to add information that wasn't visible before. Apple's Weather app, for example, now displays an hourly forecast that's only available on older iPhones after you tap on the current day. The iPhone 5 is hardly an iPad, but there's enough extra room on its screen for some iPhone apps to spread their wings in a way they couldn't do before.
Size aside, the iPhone 5's display does appear to be an improvement on the one in the 4 and 4S. Colors appear more saturated and blacks seem blacker. It's not a major improvement, but it does look better.
For people with a large hardware investment in Apple's iOS ecosystem--connecting cables, speaker docks, car chargers and the like--the iPhone 5 signifies a major transition. This device marks the beginning of Apple's replacement of the nine-year-old 30-pin dock connector with the new Lightning connector.
While Lightning-to-30-pin adapters will be available, this will almost inevitably mark the death knell for many older accessories. When Apple dropped FireWire support from the dock connector a few years back (a midstream change that many people seem to have forgotten), several of my chargers and a speaker system just stopped working. I bought a FireWire-to-USB adapter, but never really used it because it didn't fit well and using it was awkward. Lesson learned. This time I'm going to be wary of buying adapters to patch up old systems. I think I'll save my money and buy new accessories when I need them, rather than trying to stave off obsolescence with a series of ugly, ill-fitting adapter hacks.
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