Apple have today announced the iPhone 4S, the latest incarnation of the iPhone, which will be launched on 14th October 2011.

Whilst some people were surprised that this new iPhone was not radically different in looks from the iPhone 4 or was not called the iPhone 5 it is clear that this is a completely redesigned phone utilising the iPhone 4’s existing exterior.

So other than it looks the same as the iPhone 4, what defines the iPhone 4S?

Speed – The most significant specification change to the iPhone 4S from its predecessor is the bump to Apple’s A5 dual-core processor, which is twice as fast as the iPhone 4 with seven times the graphics speed. While the speed increase will enable developers to do new things by utilising a superior graphics engine in their apps, it won’t really make a fundamental difference yet. Perhaps the best reason to opt for the iPhone 4S’s faster processor is that it should help run future versions of iOS better, as was the case for the 3GS.

Camera - The iPhone 4S bumps the resolution of its digital stills from 5 megapixels to 8 megapixels and its HD video capture resolution from 720p to 1080p. The improvement, particularly in conjunction with the speedy shot time and home screen camera launching feature of iOS 5, continues the new emphasis on imaging. Indeed, there are now a host of add-on lenses created for the iPhone 4 that should work well with the iPhone 4S’s identical body.

Memory – The iPhone 4 was launched with 8GB, 16GB and 32GB memory options. The new iPhone 4S is available with 16GB, 32GB and a massive 64GB option.

Siri - The showstopper of the iPhone 4S launch was the announcement of the Siri app that is integrated into core functions of the handset as well as Wolfram Alpha for getting answers directly from the internet. Just talk to Siri as you would to a person: “Do I need an umbrella?” or “Any great burgers around here?” or “Where’s the closest ATM?” Siri not only understands what you say, it knows what you mean. It figures out the right apps to use to find the right answer. Then, just like a personal assistant, it answers you. Siri makes phone calls, sends messages, schedules meetings, sets reminders, and more. How much more? Just ask, and Siri tells you that, too.

Apple announced that the iPhone 4S was now a World Phone meaning it can roam on all global networks including US CDMA. Previously, the iPhone 4 came in two separate models (GSM and CDMA). Improvements have also been made to the internal aerial, with the iPhone 4S having two aerials that automatically switch to the best signal, even during conversations.

To some there are two main failings of the new iPhone 4S, a change in the physical design and a larger screen, which would have both been welcome. The question is, does the improvements to the iPhone 4S justify an upgrade from the iPhone 4?