Siri, like it or not, popularised voice control and is seen by many as the leading system on smartphones today.

What Siri excels at, particularly in comparison to some of the other systems in this test, is understanding natural language.

For example, Say "I want to take a picture" and Siri will open the camera app or you can just say "open camera".

It's also really good at recognising what you're saying and giving you pointers along the way if you're new to the phone. For example, you can send email using Siri but if you haven't set up your account first it will tell you to do that, rather than just return an error.

The range of functionality with Siri is quite broad but dependent upon the key partnerships Apple has put in place, so can vary depending on what you are trying to do. It's tied into most of the core apps in iOS so making or changing a calendar entry, sending a text, or getting information about a particular event is a breeze.

However, at points the information is very superficial, for example, asking when the next Formula One race would take place returned the correct answer immediately but when I asked where it was, Siri just repeated the date. Similarly, when I asked when the last race of 2013 would be, Siri said it could not get information about Formula One and offered to search the internet instead.

One of the strengths of Siri is the tie-in with Wolfram Alpha giving great results for computational answers. Ask Siri a maths question and the answer will pop straight up but ask it to switch on Bluetooth and it can't help you out.

When I asked Siri to "take me to London Bridge" it replied by popping up information about London Bridge, as well as saying how far away it was.

Siri's biggest weakness (in the UK at least) for me is the local information. Ask where the nearest Nandos is and it says "I don't know what that is" and offers to search the web.

You can also use Siri for things like taking notes, playing music or videos, checking the weather or listening to notifications.