In person? It's pretty much the same story. The iPhone 5's speed boost is most noticeable on more processor-intensive apps such as games, but apps open almost immediately and there's no waiting when switching between interface elements. Suffice it to say it's fast.
Apple claims the iPhone 5's battery life is roughly comparable to that of the iPhone 4S, and in my use I found that was roughly the case. Our lab tests of the phone playing a movie in Airplane Mode suggest that its battery life under those conditions is slightly less than the previous model. In a workday of using LTE during my public-transit commute and Wi-Fi at the office, the battery seemed to drain much the same as the battery on my iPhone 4S.
If you were hoping that Apple's latest phone would dramatically improve the battery life of the iPhone, this won't be good news. Clearly Apple has a target amount of battery life for its devices that it thinks is reasonable, and beyond that it will seemingly always opt for smaller, thinner devices over packing in a humongous battery. (Apple doesn't seem interested in releasing an iPhone Maxx, if you get my drift.) If your life demands a battery that can go a day and a half of hard usage without a charge, you'll either need to invest in a battery pack or buy a different brand of phone.
Then there's the LTE networking. I got my first taste of LTE networking earlier this year, when I bought a Verizon Wi-Fi access point, and then later I got to test an LTE-enabled third-generation iPad. In both cases, I was often able to get a faster connection via LTE than on my office Wi-Fi network. In the best situations, LTE speeds make you feel you're on a Wi-Fi network even when you're not.
As with anything cellular, your LTE mileage may vary. In our offices in downtown San Francisco, I was able to measure download speeds of 20Mbps on AT&T and 23Mbps on Verizon. Upload speeds were 17Mbps (AT&T) and 14MBps (Verizon). Compare this to the 4Mbps downloads and 0.3MBps uploads I saw on AT&T's older GSM network. Downloads that are five times faster? Not bad.
That said, LTE coverage can be spotty. Verizon's got the largest LTE coverage in the U.S., though AT&T is rolling out its network rapidly. (Sprint is even further behind.) In San Francisco, I was able to get LTE from both carriers, though outside the city the coverage fell back to older connections pretty quickly. If you're in a city not served by AT&T's LTE network, you'll want to consider Verizon.
Verizon also tends not to play games with its iPhone users the way AT&T does: While iOS 6 supports FaceTime calls over a cellular connection, AT&T has disabled this feature unless you upgrade to a more-expensive Mobile Share plan. You can use other video-chat apps without any penalty; AT&T is just holding FaceTime hostage in order to cadge more money out of its customers.
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