It's not often you can say truthfully that a piece of hardware has changed an entire industry, but such is the case with the Apple iPhone.

Nearly two years have passed since it was first launched and none of the established mobile phone brands have yet come close to matching the iPhone's effortless blend of elegant hardware and joyous user interface.

The iPhone 3G is the second iteration of the iPhone and - as the name indicates - the main difference from the original is that the sluggish EDGE aerial and chipset has been upgraded to full 3G HSDPA connectivity.

Physically the most obvious change is that the distinctive silver metal back has been replaced by a glossy black plastic one. Many still prefer the original design even though the new handset feels a tiny bit smaller in the hand, but there's little doubt that the plastic cover has boosted the effectiveness of the phone and wi-fi reception.

From the front, the iPhone is nigh on identical to the original - but then why change the stunning brilliance of the high resolution (163 DPI), touchscreen, glass-fronted 3.5-inch display? 18 months on and it still outshines every other handset on sale both in terms of its visuals and its response to touch input.

The addition of a GPS antenna is the other main hardware upgrade to the iPhone 3G. Which means that the much maligned 2 megapixel flashless camera looks increasingly puny as cheaper handsets sporting 8 or even 10 megapixel sensors arrive in the market.

But Apple obviously believes that iPhone users are willing to put up with its limited photographic - and non-existent video - capabilities in favour of its undoubted strengths.

User interface
The first and foremost of these is the user interface which, to be blunt, makes decades of software development by companies such as Nokia and Sony Ericsson look utterly wasted in comparison.

Put an iPhone in a person's hands and within minutes they will happily be doing tasks - such as browsing the web, sending email or installing new applications - that they would take hours, days or weeks to learn to do on a traditional mobile phone. If they managed it at all.

Obviously it's hard to quantify an attribute such as usability - and this is one of the reasons why the legions of iPhone naysayers who are obsessed by tech specs and price points now stand humbled and baffled by Apple's success.

The operating system, now up to version 2.2.1, has ironed out some of the quirks that attracted criticism with the original release. The random call drops still occur but they are far less frequent than they were.

You can now - hallelujah! - use search to find a contact, although frustratingly the email application is still search-free. The OS is much more stable than, say, Symbian and has a mature look and feel that belies its comparative youth. Windows Mobile looks positively prehistoric in comparison.

The App Store arrives
The latest addition to iPhone's armoury, and one that all its smartphone rivals have rushed to imitate, is the App Store. This online software shop can be accessed via 3G or Wi-Fi and stocks over 15,000 free and paid-for applications.

Admittedly scores of these are puerile (iFart) or makeshift (how many iLights can one man need?) but many more are excellent examples of productivity, utility and gaming software.

In just a few months the App Store has created a thriving software industry where developers can literally make hundred of thousands of dollars in a few days. And the main reason is because it it is so easy to find, buy and install new applications onto your iPhone, thanks to the seamless integration between the hardware and software - and the state-of-the-art transaction engine provided by iTunes.

Indeed so may feel it almost too easy, as you can clog up your precious screen space with scores of games and utilities. But Apple can hardly be blamed for making things to easy for its customers.

Similarly the oft-repeated criticism of the iPhone's battery life doesn't stand up to scrutiny. The fact is that people to do more with their iPhone - browsing the web, watching videos, listening to music, using applications - because it is so easy to do and because the iPhone is so darned good at it. And doing all this stuff hammers the battery and ensures that the iPhone requires a daily recharge where other less well used smartphones do not.

It's not perfect however. The ability to cut and paste text is conspicuous by its absence. As is the ability to send and receive MMS messages or use Bluetooth for anything but the most basic headset connections. And for many avid text and email junkies the lack of a hardware keyboard will remain a dealbreaker.

But despite these real and perceived flaws the Apple iPhone 3G still stands tall at the summit of the smartphone landscape. Even at this late stage in its product cycle it remains peerless as a mobile web browser, video/audio player, its software support and its all-round usability as a phone. It nearly matches BlackBerry as a push email platform and it gives Nintendo and Sony a run for their money in the mobile gaming stakes.

And as Sony, Nokia, HTC and the rest all rush to announce legions of iPhone killers that attempt to match where Apple is today, the inevitable fact is that in a few months time the iPhone hardware and software will be upgraded again. The goalposts moved. The paradigm shifted. The naysayers silenced.

The arrival of Apple has forced a somewhat smug and self-satisfied industry to wake up and take stock of its hardware and software offerings. We will all benefit from the fallout as products and services race to catch up, but in the meantime the iPhone 3G is the best smartphone money can buy.