I also didn't feel the heat from the 64-bit processor that some commentators have feared. The iPhone 5s runs at the same temperature as its predecessors.
Except when the LTE radio is straining, that is — LTE is supposed to be fast with data transfer, but I live and work in parts of San Francisco where LTE is rarely faster than standard 3G on Verizon or AT&T and is often unavailable on Sprint or T-Mobile. In my home neighborhood, Verizon's cellular service has been steadily degrading, so data transfers (both 3G and LTE) slow to a crawl and devices' radios work over time to maintain a connection. On the iPhone 5s, this resulted in a noticeable warming of the device in my shirt pocket. (I don't experience the warmup in my LTE-equipped iPad, whose radio strains to get a decent Verizon signal in the same places the iPhone 5s does.) Whenever I connected to Wi-Fi or entered a better-quality cellular zone, the iPhone 5s's heat dissipated.
Another dormant feature in the iPhone 5s is its M7 motion coprocessor, which lets the device compute motion and related analog signals even when the A7 is asleep. The M7 promises to both save battery life and allow long-term monitoring for everything from your daily activity to input from remote sensors like the Fitbit. But we need apps and peripherals designed to use the M7 to really see what it can do.
The fingerprint sensor makes the iPhone 5s even more secure
Most of the foolish commentary around the iPhone 5s involves its Touch ID fingerprint sensor, which was immediately attacked for not being 100 percent secure or meeting the needs of spy agencies. Quickly, hackers showed how they could use high-resolution images to create casts of people's fingerprints to fool the sensor. I don't know about you, but very few people are the targets of such "Mission Impossible"-style hacking efforts. It would be easier to guess our passwords.
The truth is that the fingerprint option ups the security of the iPhone 5s. Contrary to what you've probably read elsewhere, it's not true that the fingerprint reader replaces your password. It is a shortcut to your password; in fact, you must have a password to use the fingerprint reader. The fingerprint reader simply enters that password for you to unlock the device and/or authorize iTunes purchases. You choose which of these options, if any, is enabled, and you need to enter your actual password to adjust these settings.
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