We've always been fans of the iPhone at PC Authority, but rather than taking the opportunity to dominate its rivals in all departments, Apple's policy to drip-release features such as 3G, GPS and turn-by-turn satnav has allowed challengers to jam an ugly boot in the door. With the new iPhone 3GS, however, the door has been firmly shut.

The 3GS isn't what you'd call a revolutionary upgrade. The anticipated HD screen hasn't materialised, the camera still has no flash, and there's no change physically. The iPhone still boasts a 3.5in screen with a resolution of 320 x 480, it still measures a pocket-friendly 62.3 x 12.6 x 115.3mm (WDH), and the 3GS weighs a mere two grams lighter than an iPhone 3G at 133g.

So why the outpouring of Apple adoration? It's because, with the introduction of iPhone OS 3, the company has removed most of the previous phones' annoying limitations.

The complete consumer smartphone: Camera improvements, storage upgrade and general performance improvements on the iPhone 3GS iron out nearly all the annoyances we had with previous versions (though battery remains an issue)

Third party GPS software
Chief among these is the ability to run third-party satnav software. Ever since the dawn of GPS on the iPhone 3G, owners have been able to see their position plotted accurately on Google Maps. But in-car guidance remained restricted to an onscreen list of turning instructions. No more.

TomTom has announced it will be selling a satnav app very soon, and Navigon already has its MobileNavigator application available for download from the App Store. With the latter, the iPhone 3GS becomes a well-priced alternative to a full-blown satnav device, and in time we're sure more developers will weigh in with their own offerings.

While we're on the subject of mapping, the 3GS now has a built-in digital compass - a handy addition that makes pinpointing your position much easier using Google Maps. Rather than having to walk along the street for a hundred yards or so to determine which direction you're facing, a simple glance at the position marker - which features a built-in direction indicator - will tell you all you need to know.

Direction finder: the digital compass is a handy addition for using with Google Maps

MMS and a better camera
There are other long-overdue additions. The iPhone can now do MMS messaging, it can shoot video at 640 x 480 and 30fps, and the stills camera has also been improved from 2 to 3 megapixels.

It's an autofocus camera, but there's also a semi-automatic mode for those who want to get more creative. This means, if you're unhappy with the results of the camera's autofocus, all you have to do is tap the part of the image you want to be in focus and, hey presto, it's fixed. Plus, there are basic video-editing and upload tools, which allow you to quickly trim and send footage directly to YouTube. It's still no match for dedicated cameras, or even top-end camera phones, but for impromptu recordings and snaps it's a respectable shooter. And the 3GS is available in 16GB and 32GB variants now, too, leaving plenty of room for recorded home movies and pictures.

Cut and Paste
Then there's cut and paste. Finally, you can highlight text, cut or copy it, and paste it somewhere else. And the facility works just as well for plain text as it does for sections of web pages. Simply hold your finger to the screen, tap Select and drag the onscreen handles to highlight a section, then tap Cut or Copy. Quite why it took Apple so long to come up with such a system is beyond us, because it works like a dream.

Improved performance
The company is also keen to promote the 3GS' improved performance, and we're happy to report that it is a more responsive phone. With the help of a beefed-up ARM processor and PowerVR SGX graphics (a similar spec to the forthcoming Palm Pre) web pages render more snappily, panning and zoom feels quicker, while scrolling in Google Maps is smoother.

Voice controls
We're less enthusiastic about the voice controls: we've seen these before on Windows Mobile and S60 phones, and we've found little use for them. The internet tethering feature, which allows you to use your iPhone as a USB or Bluetooth 3G modem, isn't the cheap alternative to USB dongles it ought to be, given the cost of megabytes on most plans, but it works well.

Voice Control: A good idea in theory, but we're to be convinced on its usefulness

Battery Life
And, although claimed battery life has been slightly improved, our tests failed to reveal any advantage. We were unable to test the phone as thoroughly as normal due to time constraints, but our quick tests suggest that three days of light use, with GPS, Bluetooth and push email switched off, wouldn't be far off the mark. The 3G we tested in our most recent Labs managed four days, albeit in more amenable circumstances.

OS upgrade or new phone?
Finally, the fact that many of these improvements are also now available to existing 3G owners via the OS 3 upgrade, which is free, somewhat dampens our overall enthusiasm. The camera improvements, storage upgrade and general performance belong exclusively to the 3GS, but everything else can now be had on a standard 3G - including the satnav features. Just bear in mind that map data can occupy large amounts of storage if stored locally; this makes the 3GS a more practical navigation partner.

Conclusion
But despite all that, and the fact it's more expensive, there's simply no getting past the fact that, whether you buy the 3G or this 3GS, the iPhone is now the complete consumer smartphone. There remain some annoyances, such as its inability to download certain attachments, and the fact that you can't edit Office documents out of the box, but with the App Store ready to come to the rescue in many cases, it's now very hard to find a reason not to buy one.