Apple has unveiled its latest iPhones in a bid to compete with rivals in the growing smartphone market.
The iPhone 5S and 5C was revealed at special launch event in Cupertino, California, on Tuesday night and includes a 'Touch ID' fingerprint sensor and a range of new colours.
The iPhone 5S will run on an A7 chip, making it 20 times faster than its predecessor, the iPhone 5, and the world's first 64 bit mobile phone. It will be available in silver, gold and slate.
A new suite of motion-tracking sensors will be routed through another chip - the M7, which monitors the movement of users. Apple said this addition will promote better health and fitness among 5S owners.
The fingerprint sensor, while not unhackable, will help to deter theft.
The new camera includes a 15% larger sensor and a wider f/2.2 aperture and a 'burst mode' which allows users to shoot 10 pictures a second.
The battery life, which has been a complaint of previous models, will be two hours longer with up to 10 hours talk time and internet usage.
The 5S will cost £709 for the top 64GB model, while the 32GB will be £629 and the 16GB device £549. The starting price is £20 higher than the iPhone 5, making it more expensive than competition from the likes of HTC, Samsung and Sony.
"The iPhone 5S certainly looks good on paper. With its revolutionary inclusion of a fingerprint sensor in a mass-market phone, which could potentially remove the need for passwords and truly enhance the user experience, Apple could be on to a winner," according a review by The Guardian.
"However, the rest of the phone is just as it was for the iPhone 5, and you would be pushed to tell the difference between them from a quick visual inspection. Of course, the internal parts have been upgraded, and the new camera system could make a real difference to your photos."
The iPhone 5C is a cheaper plastic version which comes in white, yellow, red, blue and green.
It has a polycarbonate casing reinforced with a steel frame that also acts as an antenna, making it the most durable iPhone to date.
However, some critics believe the 5C is not worth the £469 for the 16GB version and £549 for the 32GB model as it is "simply a re-packaged iPhone5".
Yet contract prices will be lower - in the US they're set at $99 and $199 for 16GB and 32GB respectively.
"Although the 5C is being touted as one of the 'new' iPhones it's really just a re-packaged handset, sporting the same innards and screen resolution as the iPhone 5," according to a critic on The Telegraph, who suggested that the previous model would be knocked down in price anyway once the new model is released.
"This seems geared towards encouraging sales of the 5C, essentially asking more people to buy a new model, even if all they're really buying is a colourful case."