Apple surprised many when it introduced its new iPhone 4S. Not because people weren’t expecting a phone. They were just expecting a different one.

Rumours surrounding the iPhone event had suggested that Apple would jump straight to the iPhone 5 (or maybe even release two phones at once). As it turned out, the company followed the same course it took in 2009 when the iPhone 3G gave way to the iPhone 3GS.

That means there’s still an iPhone 5 out there, being prepped for a future release – most likely next year, if Apple sticks to schedule. So if you’re in need of a new iPhone, should you hold out for a (still-hypothetical) iPhone 5?

1 Siri really is as cool as it sounds… 

The iPhone 4S’s new features range from impressive to jaw-dropping.

The biggest stir has been caused by Siri, the voice-powered assistant built into the iPhone 4S. There’s no doubt Siri is a window into the future. Siri’s ability to understand natural language, and to remain contextually aware of the current conversation, is remarkable. Here’s a transcript from Apple’s Siri video:

Woman: Is it going to be chilly in San Francisco this weekend?

Siri: Not too cold. Maybe down to 61 degrees in San Francisco.

Woman: What about Napa Valley?

Siri: Doesn’t seem like it. It won’t get below 68 degrees.

2 …and the dictation feature is less cool, but very useful

Though Apple barely glossed over it, the iPhone 4S also supports dictation anywhere the virtual keyboard appears. That’s a feature Android phones have offered for some time, and its appearance in iOS is a welcome one. Composing small snippets of text (for emails, tweets, and messages in the iMessage feature of the iOS 5 update) could get much easier.

3 The best iPhone camera ever

Almost as exciting as Siri - and potentially offering a larger practical benefit in real-world situations - is the iPhone 4S’s heavily enhanced camera.

It offers eight megapixels, coupled with the phone’s ability to take in more light than the iPhone 4’s camera could – and those two improvements alone would be plenty. But Apple says the iPhone 4S’s A5 chip offers an image signal processor that rivals those in modern DSLRs, vastly improving colours and white balance. And the camera can now snap its first picture in barely more than a second.

4 The best video

The 4S shoots video at 1080p, compared with the iPhone 4’s 720p. And the power of the A5 processor enables Apple to offer image stabilisation of video as you shoot it.

5 The quickest iPhone yet

Thanks to the A5 chip that powers the iPhone 4S, the smartphone is comparable in speed to the iPad 2. This is the most powerful iPhone Apple has produced. Turn to our review on page 46 for more detailed speed testing.

6 …with more speed to come 

And the chances are we’ve not seen the best of the A5 processor. Give it a few months and apps will be consistently written to take advantage of the dual-core hardware.

7 Faster data downloads, and an improved web browsing experience

Improvements to the HSDPA chipset allow faster throughput on 3G data down/uploads. Which, combined with the greater processing power in the 4S’s innards, should transform your browsing experience. Once again, we’ve got figures for these improvements in our review.

8 Console-standard, high- def gaming

Thanks to that A5 processor, the 4S offers graphics that are seven times quicker than the iPhone 4, which opens up a world of console-standard games. One of the highlights of the 4S keynote was the demo of Infinity Blade 2, a forthcoming title that takes iOS gaming even further beyond the ‘casual mobile gaming’ stereotype than its predecessor. This is a device with the power to handle grown-up gaming.

9 Video mirroring

And that’s not all. The wireless AirPlay facility lets you stream 720p video from an app to a TV without having to mess around with cables. The video mirroring feature in the 4S has obvious and valuable applications for businesspeople doing presentations, for teachers, and for many others – and gamers are licking their lips too.

10 Enhanced antennae

The ‘death grip’ issue with the iPhone 4 wasn’t as big a deal as some of the haters made out, but the improved antennae on the 4S mean it’s been sorted out completely. The only way to mess up the antennae is to cover the edge of the entire iPhone with your hands.

11 Bluetooth 4 support

Bluetooth 4 offers the same speed as earlier Bluetooth standards, but with a markedly better battery life. Which could come in handy if you buy compatible peripherals.

12 Get iOS 5 out of the box

iOS 5 is the biggest upgrade to Apple’s mobile operating system in years, bringing more than 200 essential features to the table, from iMessage and Newsstand to Reminders and Notification Centre. But as many of us discovered in the days following the roll-out, upgrading from iOS 4.x to iOS 5 can be a painful experience. Grab an iPhone 4S and
iOS 5 is on there already, ready for you to discover its many treasures.

13 Power-efficiency

The improved power-efficiency of the A5 chip means that, in theory, you should expect around an hour extra 3G battery life from the 4S, as compared with the iPhone 4.

14 You won’t regret it, even when the iPhone 5 comes out

If you own an iPhone 4 today, it’s still an amazing device; the iPhone 4S hasn’t changed that. It looks good, sports the Retina display, takes nice pictures, and works well. And let’s not forget that many people still rock the iPhone 3GS – another perfectly fine phone.

Well, by the same token, if you’re eager for a new iPhone now and buy the iPhone 4S, you won’t regret your decision if Apple releases an iPhone 5 time next year.

The iPhone 5 will probably get a new look, and maybe it’ll be another smidgen faster or sport a slightly fancier display. Make no mistake: you’ll want it. If you’re an early adopter, you’ll drool over Apple’s next iPhone no matter what. But if you’re drooling over the iPhone 4S already, don’t feel obligated to wait. The iPhone 4 remained Apple’s top iPhone for 16 months – the longest such iPhone tenure to date. Perhaps the iPhone 4S will hold that top spot for 20 months now. Apple’s not saying.

You can feel confident that Apple’s not going to pull a fast one and release an iPhone 5 three months from now, right after you buy the iPhone 4S. That kind of iPhone switcheroo would alienate every iPhone 4S customer, and you can be certain that Apple’s learned a lesson about taking care of early adopters.

15 Sell now and get a good price for your iPhone 4

If you want to buy the 4S outright and sell your iPhone 4 on eBay, you’ll find that iPhone 4s are currently selling for a good price; at press time there were several on ebay.co.uk going for well over £300. Upgrade now and you can sell your old phone for a small fortune. Wait around and the price of your iPhone 4 will fall.

16 Pass on your iPhone 4S and pick up some Brownie points

Whether you’re passing on your old  smartphone to a relative in need, or conscientiously donating to a charitable or eco-friendly recycling scheme, upgrading your smartphone can present you with the opportunity to do a nice thing. And hey, spending money is good for the economy.

17 Bragging rights

This one shouldn’t really be an issue, but let’s face it, having the latest phone is cool. And who wants to be left out when everyone else is comparing notes on Siri?

18 Keep the same accessories

When Apple produces an iPhone with an entirely new body shape, accessory makers rub their hands with glee, knowing that millions of smartphone owners will shortly be looking for cases and sleeves to fit their new phones. But the iPhone 4S has almost the same chassis as the 4 - except for slight variation in the positioning of the volume and mute buttons, so beware if your case has openings for these that are particularly tight - so iPhone 4 owners may well be able to keep their accessories.

Hey, that could be a tenner you’re saving.

19 Forget the name: this is a massively upgraded phone

Apple called the 4S the 4S because it looks nearly identical to the iPhone 4, and because it’s an internals-only makeover. The rumour mill wrongly predicted that Tim Cook and company would unveil a device called the iPhone 5, but it’s not Apple’s job to correct such rumours or set exact expectations in advance. So even if we thought we’d meet a new phone called the iPhone 5 packed with new features, we needn’t be let down by the introduction of the iPhone 4S instead. We were mostly right: there’s an impressive new iPhone on the market. It’s just that its name isn’t precisely what we expected.

… AND IF YOU HAVEN’T GOT AN IPHONE 4…

In this feature we’ve focused on owners and prospective owners of the iPhone 4, and explained why they should turn instead to the iPhone 4S. But we’re dimly aware that for one reason or other, some of you haven’t bought an iPhone in a while. And some of you have even been known to purchase smartphones by rival companies. If that describes you, then you really, really need to get an iPhone 4S. And here’s why.

20 iPhone 3GS: Contracts

The 3GS has continued to be a going concern during the iPhone 4’s run at the top of the range, just as the iPhone 4 will keep selling units into 2012. But 3GS owners are now two generations out of date - not to mention likely to be coming to the end of the two-year contracts that dissuaded them from upgrading last time round.

21 iPhone 3GS: Retina screen

Compared to the 3GS, the 4S can add the Retina screen to the list of hero features listed above. Retina was a serious step forward in screen clarity. Apple claimed at the time that it offered as much detail as the human eye was able to perceive; regardless of whether you buy that, the difference between the 3GS’s 480x320 display and the 960x640-pixel screen on the 4 and 4S is impossible to miss.

22 iPhone 3GS: Camera

And when it comes to the camera, the 8-megapixel model on the 4S makes the 3GS’s 3-megapixel camera look positively prehistoric. Well, maybe not prehistoric, but at least Elizabethan.

23 iPhone 3G

If you’re still using an iPhone 3G, you’ve got all the reasons to upgrade listed above, plus one more that’s an absolute killer: you don’t get to use iOS 5. And we can’t praise that operating system highly enough. No iMessage; no Newsstand; no wireless syncing and PC-free setup; no Twitter integration. None of the many small enhancements that make things easier for those who’ve upgraded.

24 BlackBerries

With iOS 5’s iMessage app, Apple has produced a classic riposte to the BlackBerry Messenger service so beloved of younger smartphone users. The move turned out to be presciently well-timed, in fact, arriving as it did in the midst of a large-scale, three-day outage that brought down BBM across the globe.

Apple fans had problems of their own, of course, with widespread iOS 5 installation issues reported by angry iPhone owners; and a service blip realistically won’t push too many BlackBerry users across the fence. But looking to the long term, Apple is now encroaching on one of the areas where RIM held a trump card. And Apple’s own strong suits – the largest app library on the planet, for instance, and superior touchscreen displays – still look ominously dominant.

25 Android smartphones

Die-hard Android users are unlikely to be swayed by the iPhone 4S, given that they’ve ignored the reasons to switch presented by previous iPhones: rigorously coherent hardware and software design, an arguably stronger user interface, an approval process that weeds out the malicious apps that plague Android, and so on.

But having spent many a frustrating hour battling with Android’s speech recognition function, we can add Siri to the list. It has deeper integration throughout the OS and, while not infallible when coping with broad British accents, seems markedly better at deciphering our island tongue.

26 Windows Phone 7

Seriously? Ok. Small (if growing) app library; a user experience that can’t compete with iOS; still comparatively low user uptake, meaning less incentive for developers; people will stop laughing at you if you buy an iPhone.

Final thoughts

Obviously, your next step is a personal decision. So in all seriousness, if you still use an iPhone 3GS and it makes you happy, we’d say stick with it. If you use an iPhone 4 and don’t feel motivated to buy the iPhone 4S whether because of upgrade costs or its features don’t entice you, more power to you.

But if, on the other hand, you’re fired up about the iPhone 4S, we don’t think you should force yourself to wait for the iPhone 5. The next-generation iPhone is here today; the next next generation is a giant unknown.