We've been using the Apple 3G S for the best part of three weeks now so this review has definitely seen the best and the worst of Apple's amazing new smartphone.

For the sake of brevity, let's deal with the cons first. The battery life is merely adequate - probably on a par with its predecessor. What does that mean in practice? Well if you are using it in anger - playing videos, browsing the web, using the GPS antenna or even making phone calls - you will need to recharge it at the end of the day.

But a quick reality check is in order when it comes to the 'issue' of the iPhone's battery life. This isn't just a phone, it's a mobile computer platform rammed to the rafters with processors, memory and all manner of connection chips and aerials.

We should really compare it to the battery life of laptop computers (typically 3-5 hours) rather than standard mobile phones (2-3 days). Compared with other smartphones of its calibre the iPhone's battery longevity is actually among the best - just remember to take a charging lead with you.

Other issues? Well if you're an early adopter who has spent upwards of £450 on upgrading to the iPhone 3G S you may be bit miffed when you realise there is actually nothing on the surface that differentiates it from the standard iPhone 3G.

The iPhone looks and feels exactly the same as its predecessor (although the tech specs insist it's a millimetre thicker and a gram heavier). There are no go faster stripes - they don't even label it with an 'S'. Bragging rights are in short supply - on the surface.

The need for speed

Which brings us to the end of the iPhone's debit column and to the top of the positives. As soon as you look below the surface and start using the iPhone 3G S it's immediately apparently what the elusive 'S' stands for: Speed. By the shedload.

The tech specs state that the iPhone 3G S has a 600MHz processor (up from the 3G's 417MHz) and 256MB of onboard RAM (compared with 128MB). The extra horsepower in itself may not be worh the price of the upgrade but they do make the phone a real pleasure to use.

Booting up the phone is faster, opening an app is faster, browsing the web is much faster. For instance, opening the BBC News homepage was 30% faster on an iPhone 3G S than an iPhone 3G - that may not seem like much but over time the difference between the two phones becomes more and more apparent. Once you've been using an iPhone 3G S going back to the standard iPhone becomes an exercise in frustration - even though the older phone is no slouch.

Apart from the speed hike, the iPhone 3G S has a new 3.0 megapixel camera that can take video. Once again, the statistics don't tell the full story. It may 'only' be 3.0 megapixels but the camera now has autofocus, auto white balance and a macro mode. The combined effect is that pictures look far sharper than they did before and the clever use of the touchscreen - you literally touch the element that should be the subject - means that fixing the focus and the exposure is child's play.

Of course, it's no substitute for a 'proper' digital camera but it doesn't pretend to be - it's there to take quick snaps that are not too big so they can be MMS-ed or uploaded quickly to Facebook or Twitter.

On the video front, the iPhone 3G S can capture video at 640x480 resolution at a silky smooth 30 frames per second. Once again it's not high definition but it's ideal for taking quick clips and sharing them with friends via the built-in YouTube upload app or by email and MMS.

The quality is 'good enough' - which is better than 90% of other mobile phones - and there's even a basic video editing app that lets you trim out the boring bits. People are definitely using this feature - YouTube reports that mobile phone uploads have surged 400% since the iPhone 3G S launched on 19 June.

Play 'Florence and the Machines'

Another hyped feature of the iPhone 3G S is voice control. In theory you can speak to the phone (or the microphone in the headset lead) and say anything from 'Call Tracy Thompson' to 'Play Florence and the machines'. A digital signal processing chip in the 3G S will then convert your voice into a digital command.

In practice, it worked - up to a point. The voice recognition worked OK for the most part (although it did have trouble with Florence and the Machines, but don't we all?). But the reality is you feel a bit stupid talking to an inanimate object and most of the time its far quicker to use your fingers. It will have obvious benefits for hands free situations such as driving but at the moment it promises more than it delivers.

Of more immediate use is the iPhone's digital compass - or 'magnetometer' for the geek of heart. This little wonder can detect true or magnetic North whatever the orientation of the iPhone (ie it doesn't have to be flat to work). This is displayed on the Compass app as a nifty old-style compass needle that looks like it wandered off the set of Pirates of the Caribbean.

The compass really comes into its own in the upgraded Google Maps application. When you click on the little blue dot it suddenly gets a field of view that represents the direction it (and you) are facing. As you turn around the map immediately rotates to match - an effect which is strangely hypnotic.

It's also very effective, as we can vouch - when the Tom Tom GPS conked out recently on a road trip in Tuscany, the iPhone 3G S easily took its place and guided us back to our villa by the quickest route. It really is that good - and with proper turn-by-turn navigation software in the pipeline it should get even better.

On a smaller but no less significant hardware note - Apple seems to have 'fixed' the mute switch on the side of the iPhone 3G S. As many owners of previous models will attest this has an annoying habit of switching itself to mute when bouncing around in your pocket or handbag. Now the switch is noticeably stiffer and we have yet to report an accidental mutes and crucial mixed calls. Thanks, Apple.

The crucial question: should I or shouldn't I?

Ultimately the iPhone 3G S is a speed bump and a series of small - but significant - hardware refinements rather than a major upgrade. Existing iPhone 3G owners who have months left on their current O2 contract will have to stump up a lot of cash to upgrade to the new handset.

Is it worth it? It's certainly not the case that the iPhone 3G has been redundant overnight. The year-old handset is still the best smartphone on the market - bar one.

The answer to the question is how much are you prepare to pay to own the very best smartphone you can buy? Because despite all the hyped 'iPhone killers' that have come and gone, nothing yet comes near the winning combination of power, speed, developer support and ease-of-use of the iPhone 3G S.

Despite the recession, early indications are that the launch sales of the iPhone 3G S are even higher than those of the original iPhone 3G. Millions of people have shown that they are prepared to a premium for the very best.

You pay your money and you take your choice. We bought ours on day one.