Moving up from an iPhone 4 or 4S, the improvements that "jumped" most at me were:
- the contrast ratio of the screen (thanks to a much improved — i.e., darker — blackpoint),
- the quality of low-light still photos,
- the improved rendition size of many videos (larger roughly 16:9 ratio screen), and
- the lighter weight.
The 4S never felt particularly slow, but with the iOS6 update, the 3D maps were clearly taxing the older device, whereas its buttery smooth on the iPhone 5. It's also noticeably smoother than the new iPad (which itself is smoother than the iPhone 4S). The improved performance is also felt throughout the system (app startup times, etc.), but it's usually fairly subtle,
The camera's panorama mode (also available on the 4S) is very impressive from a performance perspective, and is overall eminently usable. Right now, it's just a one-swipe panning mode. I hope Apple decides to add a mode that allows "2D" panning (like e.g. Microsoft's Photosynth app) without sacrificing the performance and usability of the current mode.
After restoring the device from a 4S backup, every "home" screen is populated as it was before, leaving an empty row just above the bottom "dock" row thanks to the taller screen. I haven't decided how to use the new space, but I suspect that once I do, it'll will be an addition to my list of most compellingly upgraded features listed above.
Battery life has not significantly improved, and while it's still better than many other smartphones I've tried, I have at least one day of the past five hit the 20% warning before dinner time (at which point I changed my usage pattern to ensure I could get calls until I got back home). That day I had used the camera considerably more than usual, which may account for much of the consumption. (One of my kids also played some games for a while, but that's not unusual.)
The ecosystem isn't bad (I'm particularly impressed how quickly major app vendors have updated their offerings for the new screen size), but the new connector and new device size do reduce options at this time (compared to the iPhone 4S). I'm feeling it the most right now in the lack of options for a belt case. There are some, but none yet that I like.
The Breakdown
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Design
10
-
Display
10
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Camera(s)
10
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Reception / call quality
10
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Performance
10
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Software
10
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Battery life
9
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Ecosystem
9