The iPhone 5S provides four major enhancements to the iPhone 5 (which, by the way, was not only the world's top selling iPhone, but the top selling smartphone as well): the new Touch ID for both security and convenience; new camera features in both hardware and software; a brand new, advanced new multiple-processors architecture that combines the speedy new A7 as well as the new M7, which provides background-task efficiency; and new radio components that provide broader LTE carrier coverage and better compatibility. They may not seem like much, but believe me, these are significant updates.
The most prominent to the eye, is the new Touch ID fingerprint sensor. The Home button is now circled by a slightly inward-sloping metal ring (used to sense your finger's presence without requiring press) in the same finish color as the sides of the device (in Silver, Gold or Space Grey).
Rather than being slightly concave as with all previous iPhone Home buttons, the new sapphire Home button disc within the ring is flat. Since the ring's edge lies flush with the front surface of the device and the button within is slightly recessed, it has a similar feel to previous Home buttons.
The "click" action of the button also feels the same. If you compare older Home buttons, on the 5S there's what appears to be a slight optical illusion that makes the new Home button look smaller, thanks to the color-accented metallic ring calling attention to the button's edge.
This results in a contrast of Touch ID being both readily apparent and invisible at the same time. The software implementation of Touch ID is also purposely invisible.
The TouchID has no movie-style depiction of "scanning… authenticated!" with animations, buzzing or flashing lights for feedback. It just works, you touch the Home Button, your iPhone 5S unlocks.
What Touch ID does
iOS 7 currently uses two features for the Touch ID sensor: Passcode Unlock and iTunes & App Store purchasing. This gives Apple the ability to focus entirely on getting the initial experience right, rather than unleashing a multitude of half baked feature concepts, or erring in other ways that would be worse than never having implemented Touch ID at all.
In practice, being able to log in with a finger press is both a quick convenience and an intuitive simplification over having to manually type in a passcode, similar to having a proximity key that lets you get in and start your car without requiring a physical key. The Touch ID convenience hopefully makes it much more likely that you'll create and use a passcode, and set your phone to lock immediately.
Apple says half of its users are not currently using a passcode, and it's likely that many of those who do, set a delay so they don't have to type it in the passcode every time they wake their device. With Touch ID, it's much more practical to have your phone locked all the time. Logging in with a finger touch is almost as fast as unlocking the phone without a passcode.
Touch ID certainly was not created to make your iPhone 5s impenetrable to spy agencies. But the reality is that Touch ID is far more accurate, faster and more secure than a simple passcode, or any of the alternatives on the market: the 'swipe to unlock' gesture used by Android OS, or the Face Unlock experiment. The latter provides a great example of how being first to market in a category is not better than being first to market with a great product (Touch ID).
Apple hasn't just beaten Samsung and others to market with workable fingerprint login as a feature, but it's made it known that Touch ID enhances security and can deliver a great product, rather than being an invasive spyware tool designed to collect information about users and what they do, as Samsung did when it gave away a "free" music app in Google Play to its Galaxy customers. Who could trust Samsung or Google with their fingerprints after that disaster?
Further enhancing the Passcode Unlock functionally of Touch ID is iOS 7's new Activation Lock capability, a new feature that activates automatically when you configure a device with a free iCloud account and turn on "Find my iPhone."
Activation Lock links the device's activation process with its firmware ID and your iCloud account, so if your device happens to get stolen, the jackass thief who took it can't simply wipe it for quick and easy resale. Apple's answer involves something it has that the Android platform does not: a centralized activation process.
The security provided by the Activation Lock is similar to carrying a credit card instead of cash. Thieves can still hold you up, but they can't be guaranteed any payoff. Activation Lock is a welcome deterrent to would be attackers.
Activation Lock available to those with an iPhone 4 and forward via the free iOS 7 update. Using Activation Lock doesn't require a passcode, and turning off iCloud's Find My Phone isn't possible without your iCloud account.
Using Touch ID with iTunes & App Store
The other (optional, but highly recommended) use of Touch ID is to authenticate purchases in iTunes and the App Store. Apple currently requires you to sign into your account to make a purchase, and sign in again every 15 minutes. If you already have a secure Touch ID fingerprint configured, you can bypass signing in by turning on this new Touch ID feature.
When you first activate iTunes purchasing, you are asked for your iTunes Apple ID password. Subsequently, you can use your fingerprint instead, Awesome! Apple's priority for Touch ID is clear, to secure your devices. However, the infrastructure behind Touch ID as a passcode clearly has broader applications, and the fact that Apple is launching it with iTunes suggests additional plans for Touch ID for perhaps to authenticate sales and also adding security to other transactions as well.
Touch ID instantly makes it more convenient for Apple's iPhone 5s customers to make iTunes and App Store purchases. It doesn't require signing up for new accounts, and doesn't replace one easy swipe with another easy tap; it replaces a moderately annoying password prompt interruption with a finger touch, again, Awesome! Once Apple has more experience with how its customers are using Touch ID, it can, and I sure will, move development forward.
I hope this review is helpful, I'd love your feedback!