Apple's scanner is seen as a first step toward realizing the full potential for biometrics in personal electronics, heightening security for applications like banking and shopping while doing away with multiple passwords.
(Also see: Apple unveils iPhone 5c and iPhone 5s)
"The best part is that it actually works - every single time, in my tests," wrote reviewer David Pogue of the New York Times.
(Also see: 10 new features in Apple's iPhone 5s)
"It's nothing like the balky, infuriating fingerprint-reader efforts of earlier cellphones. It's genuinely awesome; the haters can go jump off a pier."
The Wall Street Journal's Walt Mossberg was also enthusiastic, calling it simple and reliable. But he noted that the gadget would inexplicably prompt him for a password when swiping a finger to make purchases, which he blamed on a bug.
"I have come to like it and consider it a step forward, despite a few issues," he said of the overall device.
Re-tooled iOS7 (Review) mobile software, a better camera, a more useful voice-activated "Siri" personal digital assistant and a faster processor combined to make the iPhone 5s (Review) the best smartphone on the market, he added.
However, he argued that owners of the previous-generation iPhone 5 may not have a compelling reason to buy the latest device unless they specifically wanted the fingerprint reader.
(Also see: iPhone 5s and iPhone 5c: 10 big improvements)
Many industry analysts view the iPhone 5s and the cheaper iPhone 5c as being modest improvements on the previous generation, reviving fears that Apple's most innovative days may be behind it. They said the mere fact of a fingerprint scanner was unlikely by itself to make the gadget a sure win in a crowded market.
Apple has embedded the scanner into the iPhone's home button, while other mobile devices usually have it on the back, making it awkward for the user and increasing the number of failed attempts.
(Also see: iPhone 5c vs. iPhone 5s vs. iPhone 5)
Archrival Samsung Electronics Co Ltd and fellow South Korean electronics manufacturer LG Electronics Inc have had problems incorporating the technology into finished products.
© Thomson Reuters 2013
For the latest tech news and reviews, follow Gadgets 360 on X, Facebook, WhatsApp, Threads and Google News. For the latest videos on gadgets and tech, subscribe to our YouTube channel. If you want to know everything about top influencers, follow our in-house Who'sThat360 on Instagram and YouTube.