The iPhone 5s, like its cheaper sibling the iPhone 5c, has been available for a few weeks now, earning plaudits from most reviewers and igniting ignorant online discussions around mobile security and application performance. Some of that ignorance is intentional FUD from Android fanboys and security purveyors.

The truth is straightforward: The iPhone 5s lays the groundwork for the next generation of Apple mobile devices, introducing the 64-bit architecture to its processor, operating system, and applications as well as making it easier to secure mobile devices, thanks to its fingerprint reader. (As for the iPhone 5c, it's last year's iPhone 5 in a nice-looking and nice-feeling colored plastic case with an improved camera, and it runs iOS 7 -- enough said.)

The Touch ID fingerprint reader in the iPhone 5s is the most visible improvement in the new Apple smartphone compared to last year's version, the iPhone 5 . Apple calls attention to the reader with the metallic ring that now encircles the Home button. You may also notice a second, amber LED on the back of the iPhone 5s, which helps produce more accurate skin tones when taking photos with the flash.

Except for these two clues, the iPhone 5s and iPhone 5 look, feel, and weight about the same. (The iPhone 5s also comes in a surprisingly subtle gold finish , a new color option that the iPhone 5 did not have.) This strong similarity reflects the fact that the iPhone 5s is at heart an upgraded iPhone 5.

Yet it also obscures how the iPhone 5s sets the scene for future waves of Apple mobile devices. You can bet your bottom dollar that at least some of the new iPads expected later this month will sport both the 64-bit A7 processor and the Touch ID fingerprint reader that debuted in the iPhone 5s.

Because the iPhone 5s and iPhone 5 are so similar in many respects, I won't go into detail on where they overlap. Suffice to say you get the same 802.11n Wi-Fi, low-power Bluetooth, and LTE cellular radios as in the iPhone 5; the same high-quality, balanced-color screen; the same buttons; the same high-quality speakers (with only slight distortion despite their small size); and the same ability to use a GSM SIM card even on CDMA models (for use when traveling abroad).

The promise of 64-bit computing for now is just a promise

There's been a hullabaloo in the blogosphere around the 64-bit A7 processor in the iPhone 5s. Many pundits feared it would run 32-bit apps more slowly or chew up battery life. Neither is true. In my testing, 32-bit apps running in the iPhone 5s's 64-bit version of iOS 7 run at least as fast as on previous 32-bit iPhones. The iPhone 5s's battery life is about 15 percent less in moderate use than that of the iPhone 5, but the decrease appears entirely due to iOS 7, not to the new CPU or other iPhone 5s hardware. I've experienced the same battery life decline in a variety of iPhones and iPads after upgrading them to iOS 7.

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.

Right now, the 64-bit A7 delivers little to users. Until developers take advantage of the 64-bit processing, its potential is lying in wait. The new version of Apple's Xcode creates 64-bit apps automatically, so only now can developers start to think about how they might harness that horsepower. We should see the power of 64 bits in the next year. Meanwhile, the benefits are limited to some JavaScript optimization in the Safari browser.

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.

The controls over fingerprint and password security on the iPhone 5s.

iOS encourages you to enter a complex password, so it's harder for someone else to guess your password. (Many pundits falsely claimed the iPhone requires only four-digit PINs; that's the default option. Exchange ActiveSync policies or mobile device management servers can enforce the use of complex passwords.) The fingerprint reader enters your password if you hold an enrolled finger on the Home button when the iPhone 5s is locked or when making a purchase from an Apple store. If you've turned off the iPhone 5s, you must type in the password; the same goes if you haven't accessed the iPhone 5s for 48 hours or more.

The fingerprint hash is stored locally on the A7 chip itself and, so far, is available only to iOS itself to unlock the device and to the App Store, iBooks, and iTunes Store apps to authorize purchases (if you enabled that option). It is not synced to any server or backed up.

The fingerprint sensor works remarkably well, and you can have up to five authorized fingerprints, such as yours and your spouse's. As a result, there's less of a barrier to using a password on your iPhone and having it auto-lock when not in operation. That makes the device more secure.

I can't underscore enough how Touch ID makes it more convenient to have a stronger password on your iPhone. That's a win-win for everyone but thieves.

Speaking of security, there's also been a kerfuffle about flaws that allow users to access the iPhone from the lock screen without entering a password. This is an iOS 7 issue, not specific to the iPhone 5s. Apple corrected just such a flaw a week ago in an update. But it's true that iOS lets users access the Control Center, dial by voice, use Siri, use Passbook, reply to incoming calls via text message, and control music playback even when the iPhone is locked -- except for the ones you disable. Businesses that use a mobile device management (MDM) server can enforce policies that prohibit any or all of these except music playback controls.

Also available to any iOS 7 device, not just the iPhone 5s, is the new device lock that prevents the iPhone or iPad from being reset, reimaged, or transferred to a new carrier or owner until the correct Apple ID is entered. This is enabled by default, rendering stolen and lost iOS devices useless to black-market sellers.

Plus, iOS 7 introduces enterprise-grade application management APIs and licensing management that no other mobile platform offers. There's no other commercial device that comes close to matching the iPhone 5s's level of security -- save a BlackBerry -- and none matches its security convenience or application manageability.

Another parry in the camera wars

When a new smartphone debuts, its camera usually gets a lot of attention, and there's sort of an arms race when it comes to camera capabilities. Nokia's smartphone unit, now owned by Microsoft, has even made the camera the key differentiator of its devices.

iPhone 5s Camera app's lighting effects

Apple likes to say the iPhone is the source of more photos than any other mobile device or digital camera. Each new device also gets a photographic boost, even if Apple doesn't play the senseless megapixel games as do Nokia and some Android makers -- megapixels matter much less than the quality of the image sensor and the lens, as any professional photographer knows.

The iPhone 5s adds a second, amber LED to take more accurate images of skin tones; the device flashes both the white and amber LEDs and captures an image of both, using the pair to create the best composite image of whatever you're shooting, all in milliseconds. The bottom line is that the photos look more natural and closer to the images a professional digital camera would take.

Apple has also enhanced the Camera app to include virtual lighting filters for compatible devices such as the iPhone 5s. You can select the desired lighting adjustments, such as monochromatic or process. There are also options for square photos (new to iOS 7 on all devices), slow-motion video (new to the iPhone 5s), and autostitched panoramas (introduced in the iPhone 5), plus HDR and auto-flash options. iOS's Camera app doesn't have all the controls and adjustments that, say, the latest Android devices do, though some are available in the companion Photos app or the pro-level iPhoto app that comes free on new iPhones and costs $5 for existing ones.

The bottom line is that the iPhone 5s takes very good pictures and videos, but it's not trying to be a lightroom in a box.

Better today, better tomorrow

Both the iPhone 5c and iPhone 5s are available for the AT&T, Sprint, T-Mobile, and Verizon networks in the United States, with availability planned for smaller regional and pay-as-you-go carriers. The iPhone 5c costs $549 for the 16GB model and $649 for the 32GB model without a contract, and $99 and $199, respectively, with a two-year contract. The iPhone 5s costs $649 for the 16GB model, $749 for the 32GB model, and $849 for the 64GB model without a contract and $199, $299, and $399, respectively, with a two-year contract.

All in all, the iPhone 5s ups the ante today with its Touch ID fingerprint sensor and sets the stage for more powerful apps tomorrow with its 64-bit A7 processor and M7 coprocessor, while also better satisfying the shutterbug in you.

The iPhone 5c is mainly a repackaging of the iPhone 5, though its InfoWorld Test Center score is higher due to what iOS 7 provides it. Unless you must have one of the 5c's five M&Ms-style colors, the iPhone 5s is a smarter, longer-term option for just $100 more. It's also the best overall smartphone on the market today, though the Android-based HTC One and Samsung Galaxy S 4 may be more appealing to users who want a larger screen.

The Complete Guide to the iPhone 5s & 5c is on-sale now. Click here for buying information.