But Apple’s new flagship iPhone 5s and lower-priced iPhone 5c, both of which go on sale in Hong Kong on Friday, has attracted blistering criticism since last week, mainly for looking the same as the previously released iPhone 5, with detractors saying the tech giant hasn’t made any significant improvements to the device - apart from more colour options.

And people may also have been angered because the iPhone 5c price wasn’t as low as some people had expected.

But in the short time I had to test the two new models, I realised that they represent significant upgrades worth considering for iPhone users and for those thinking about buying an iPhone.

Would die-hard Android smartphone users be convinced to use these handsets? Not really. That question should probably wait until Apple rolls out the iPhone 6, which should be a complete redesign.

Available in white, gray and gold, the iPhone 5s delivers features that make it the most advanced smartphone in the market today.

It may look a lot like the older iPhone 5, but a closer inspection showed a more pronounced home button below its 4-inch multi-touch display, and there’s no square outline on the centre of the button. The change was made to accommodate Apple’s new fingerprint identity sensor.

Google’s Motorola Mobility was the first to introduce a built-in fingerprint reader on its Atrix smartphone in 2011, but the iPhone 5s’s so-called Touch ID is a more advanced biometric authentication system. I think it’s easier to use than the thumb identification screening mechanism used by Hong Kong immigration.

The iPhone 5s system guides a user to enrol his or her fingerprint ID. First, you have to set up a backup password, followed by a swift training session for the finger you want to use as your ID.

The stainless steel ring on the home button detects the finger the moment it is touched, alerting the sensor to scan one’s fingerprint. Once initiated, the setup process takes several touches to fully scan each finger you want enrolled. I used my thumbs, and saw on the display each line of my prints get scanned. Multiple fingerprints can be enrolled.

The Touch ID uses certain Apple algorithms put to recognise one’s fingerprint whatever the orientation of the iPhone 5s -- portrait, landscape or anything in between. You can make app purchases using just the fingerprint ID. No password needed. How convenient.

A friend volunteered to unlock the iPhone 5s. But of course, that did not work. During the course of my tests, the Touch ID sensor did not fail to recognise my fingerprints even when I touched it off centre.

The iPhone 5s is powered by a new A7 chip, which is a 64-bit desktop-class processor. It is capable of running faster and smoothly more complex graphics and detailed visual effects, once possible only on personal computers and gaming consoles.

I did not have an opportunity to test the chip’s capabilities with a 64-bit video game for smartphones. I don’t know if there is any available in the App Store - and whether I can afford it.

Still, the A7 chip manifested its processing power when I tried the new “burst mode” feature on the iPhone 5s’ iSight camera. Burst mode continuously captures at 10 photos per second, making me feel like a pro. The A7 chip delivered faster photo capture and faster auto-focus.

In reviewing my shots, the iPhone 5s provides intelligent analysis. It suggests individual pictures or a sequence of photos that I may like the best from all the shots I took.

The iPhone 5s also provides so-called Tru Tone flash that allows one to take better flash photos. It matches the flash to the ambient light temperature of the scene, a nifty trick that made me feel like a pro just by using it. A shot inside your home or or a restaurant need warmer light temperature for the flash, not the static flash found in most cameras, to get more true-to-life colours.

In terms of using the iPhone 5s on high-speed 4G networks around the world, all your problems are solved. It supports up to 13 different 4G (LTE) long-term evolution bands, more than any smartphone in the world. This includes the China-backed 4G standard called time-division duplex long term evolution.

But what also sets apart the iPhone 5s and 5c models is Apple’s mobile operating system refresh, iOS 7. Its use of translucency, subtle motion, new colour palette, simpler typography, and functional layers make the platform seem elegant and alive.

The interface also seems more intuitive, allowing for smoother multi-tasking. My personal e-mail, reading text messages and posting on Twitter were all discreetly kept up-to-date in folders, while I opened another website or app. You can press the home button twice to see the preview screens of the apps or sites you have open.

Users of older iPhone models ought to consider the new iPhone 5c, which comes in white, pink, blue, yellow and green. I own an iPhone 5, but I liked the look and feel of the iPhone 5c, which is a worthy update. I had tested it ahead of the iPhone 5s, and was pleasantly surprised.

Once I held it for the first time, the iPhone 5c sure felt like a solidly built smartphone. Its seamless, hard-coated polycarbonate case has been steel-reinforced. That reinforcement also serves as its antenna.

Like the iPhone 5s, the 5c supports up to 13 4G LTE bands, which is an improvement over the iPhone 5. It also has the advance camera functions, such as burst mode, and larger battery that provides up to 10 hours of browsing on a 4G connection. With iOS 7, it also performs better when multi-tasking and editing photos.

By all accounts, it is a premium handset with a comparatively mid-range price for those who want to upgrade from their older iPhones, or those who want to experience the Apple eco-system for the first time.