We take a look at how the iPhone 5 and iPhone 4S stack up against each other and see if it is worth upgrading.

Apple iPhone 5 versus iPhone 4S
Apple iPhone 5 versus iPhone 4S. Reuters

Apple has just announced the iPhone 5 featuring a 4in Retina Display, A6 chip, ultra-fast wireless connectivity and an iOS 6 operating system. The newest Apple smartphone is the thinnest and lightest iPhone ever. The iPhone 5 will be available in the UK on 21 September, with those really eager to get on board able to pre-order the device starting 14 September. The 16GB variant of iPhone 5 will be priced at £529 SIM-free in the UK.

"iPhone 5 is the most beautiful consumer device that we've ever created," said Philip Schiller, Apple's senior vice president of Worldwide Marketing.

"We've packed an amazing amount of innovation and advanced technology into a thin and light, jewel-like device with a stunning 4-inch Retina display, blazing fast A6 chip, ultra-fast wireless, even longer battery life; and we think customers are going to love it," said Schiller. Analysts predict that the iPhone 5 is expected to become the best-selling device.

"This is going to be the best-selling consumer electronics device of all time, bar none," said Carl Howe, an analyst at Boston-based Yankee Group according to Bloomberg. According to reports, Howe has predicted the tech giant will sell more than 10 million by the end of September.

But the question is, if you are an iPhone 4S owner, is it worth the money to upgrade.

The iPhone 4S was announced back in October featuring an A5 chip, camera with advanced optics, full 1080p HD resolution video recording and the voice assistant - Siri.

To help you decide we take a detailed look at how iPhone 5 and iPhone 4S compare in terms of hardware and software features:

iPhone 5 vs iPhone 4S: Design

Apple iPhone 5 versus iPhone 4 Design

The iPhone 5 measures 123.8 x 58.6 x 7.6mm and weighs just 112g. Being the thinnest smartphone in the world, the device comes with an anodised aluminium body which is 18 percent thinner and 20 percent lighter than its predecessor, the iPhone 4S.

The smartphone is said to be built with an extraordinary level of precision since it combines the anodised aluminium body with a diamond-cut chamfered edges as well as glass inlays.

On the other hand, the iPhone 4S weighs 140g and measures 115.2 x 58.6 x 9.3mm. The iPhone 4S features a combination of glass and stainless steel in its design.

iPhone 5 vs iPhone 4S: Display

The iPhone 5 sports a 4in Retina Display that has a resolution of 1136 x 640 pixels giving it a pixel density of 326 pixel per inch (ppi). the screen is larger but is not wider, meaning the iPhone 5 has a 16:9 aspect ratio, making viewing videos a lot better.

Making the phone the same width means using it single-handed should still be no problem, but the taller screen will mean more information will be displayed - including that fifth row of apps.

According to Apple, the colour saturation is 44 percent greater than the iPhone 4S.

The iPhone 4S screen is 3.5in in size which is the same as all other, older iPhones. It has a resolution of 960 x 640 pixels giving it a pixel density of 326ppi. While the screen is still among the best available in terms of sharpness and colour reproduction, at 3.5in it is very much at the small end of the current smartphone market.

iPhone 5 vs iPhone 4S: Processor

A6 versus A5 chip

The iPhone 5 is powered by the new A6 chip which is designed in order to maximise device's performance and the power efficiency.

The extra processing grunt will help to support features including the 4in Retina Display. Apple promise twice the CPU and GPU performance compared to the the iPhone 4S, giving the new smartphone the ability to launch the apps or loading web pages faster.

As we said, the iPhone 4S is powered by the A5 dual-core chip which most users find most than sufficient for their needs. It features a PowerVR SGX543MP2 GPU and allows for some pretty intensive 3D gaming as well as improving the capability of capturing and processing images.

One thing we've yet to discover is how much RAM the iPhone 5 will have, but its sure to be an upgrade to the 512MB available in the 4S, with 1Gb the likely figure.

iPhone 5 vs iPhone 4S: Operating System

The iPhone 5 will come pre-loaded with the latest operating system, the iOS 6. Apple announced the iOS 6 back in June at the WWDC 2012 with 200 new features including a new maps app with turn-by-turn navigation and Flyover view, Facebook integration for Contacts and Calendar, Passbook app, new Siri features and more.

The iPhone 4S ran iOS 5 when it launched, including new features at the time such as Notification Centre - in order to view and manage notifications in one location without any interruption. However the iPhone 4S will be upgraded to iOS 6 from 19 September, bringing with it all the advantages the iPhone 5 will have

iPhone 5 vs iPhone 4S: Camera

Both iPhone 5 and iPhone 4S feature an eight megapixel iSight camera with autofocus, LED flash, Touch focus, geo-tagging, a backside illumination (BSI) sensor and face detection. However, the iPhone 5's camera is 25 percent smaller than the one in iPhone 4S and features a number of upgrades.

This time, the iSight camera features a sapphire crystal lens cover which is thinner as well as durable than the standard glass. It also has a hybrid IR filter and promised to take pictures 40 percent quicker than the iPhone 4S. Making use of the widescreen display, Apple has brought a Panorama mode to the camera app, letting you stitch together a number of images to create a single wide-angle image.

Apple has also updated the front-facing camera to offer 720p HD video and for the first time FaceTime calls can be made over the cellular network - previously it was Wi-Fi-only.

iPhone 5 vs iPhone 4S: Connectivity

The iPhone 5 will support, for the first time, ultra-fast wireless 4G technology based on the LTE technology, making streaming videos and simply browsing the internet a much faster experience. For UK customers the key question was if the iPhone 5 would run on EE's new 1800MHz 4G network, and the answer thankfully is yes.

The iPhone 5 features a Wi-Fi 802.11 a/b/g/n, and promises searingly fast wireless connectivity thanks to dual-band (2.6GHz and 5GHz) Wi-Fi.

The iPhone 4S supports HSDPA, which promises speeds of up to 14.4 Mbps but this will pale in comparison to the speeds available from EE's 4G network - as we saw when we tested it earlier this week.

Both devices provide support to Bluetooth 4.0 with A2DP technology.

iPhone 5 vs iPhone 4S: Battery

The iPhone 5 features a larger battery than its predecessor but promises a similar amount of battery life because of the drain put on it by the new 4in display and the A6 processor. Apple said the iPhone 5 will provide eight hours of talk time on 3G with standby time of up to 225 hours.

The iPhone 4S features a smaller 1432mAh battery that again offers talk time of up to eight hours on 3G and standby time of up to 200 hours.

iPhone 5 vs iPhone 4S: Colour

The iPhone 5 comes in two two-tone versions: black and slate and white and silver. While, the iPhone 4S features two monotone options: black and white.