When Steve Jobs releases a new phone, it always comes with an updated firmware too - and the iPhone 4 is no different. The new iPhone OS has been dubbed iOS 4 now, seeing as it's being used on the iPad too, and it's bringing a lot of upgrades that people have been hankering for for years.
But we'll quickly run through the high points of the iPhone for the uninitiated: the same iPhone home screen is offered, where it's a simple grid of icons to select applications.
If you want to re-order these, simply long press on any one, and they all start to wobble around, allowing you to flick them in whichever order you like or if you want you can delete them by pressing the X.
You can't delete the pre-loaded applications though: for instance, nobody cares about Stocks, but you have to have it there. We'd love to know if anyone has ever created a decent portfolio based on the fact they had to stare at the Stocks icon all the time and finally cracked.
Most applications, like Settings and Contacts, take you to a menu-based system, with list options to tap and drill down to further things you can interact with. All very simple really.
But this is one of the key places the iPhone has always excelled - little animated transitions make things look so cool when they flick around under the finger, and it really makes people that try the phone for the first time think it's awesome.
iPhones of old have often struggled to keep up with these animations - talk of 400MHz processors should tell you why. But this is an ARM Cortex-A8 Apple A4 1GHz processor running things here: we're sure Apple is underclocking this to save on battery life, but it doesn't matter - each change is seamless and that's what we want.
And of course, Apple's simple way of navigation is still present - simply tap the home button at any point and you're back to the familiar home screen. Simples, as a certain member of the mongoose family may or may not say.
The main change with the iPhone 4 is the fact multi-tasking is now on offer, something that has put Apple behind the smartphone competition for many years.
Want to listen to Spotify and browse on Safari? Nope, not possible previously - but now it is, and that's what we call a Good Thing.
Of course, Apple being the gleaming machine it is, we couldn't have simple multi-tasking like on other platforms - Jobs has apparently 'solved' things with this cunning new method.
We mean cunning in an ironic, Tony Robinson-way, because essentially all that has happened is Apple has decided to control this element as well: only certain applications which have been verified to not eat all your battery and then kill your pets (well, the first one) will be allowed to run in the background, rather than all and any third party applications.
This is slightly annoying when you have things like social networking options that you want to be able to leave and come back to, and see all the updates without waiting.
But overall: Apple's way of multitasking is the right way - you simply double tap the home button, and a little row of icons at the bottom of the screen pops up, with the most recent application opened on the left.
You can scroll along to choose the running application you want and go right back in where you were before. This means an open email you're writing, a web page, video, or something like a third party internet radio.
Scrolling to the left of the icon dock again will offer two more options - music control with basic commands, and the chance to lock the orientation - handy if you need to keep twisting the phone when watching video for some reason.
Switching between the applications spins the chosen application into view in a very pleasing fashion, indicative of the way Apple does things with the iPhone.
Legacy iPhone users will be used to the plain old black background – so now being allowed to customise however they see fit is going to be a real treat.
There's no reason Apple hasn't allowed this so far, and it feels a little childish that this has only popped up (unless you were one of the unruly kids and jailbroke your iPhone – perfectly acceptable then).
However, being able to have it as both the lock screen image and the background is a nice touch, or to have two separate images if that's your bag.
The only other new and interesting feature to the interface is the addition of folders – if you're fed up of being forced to see row after row of icons you're going to find life just got a lot simpler.
Simply long press an icon, and rather than moving that little picture to a new place, dump it on top of another one, automatically creating a folder with the two applications in there.
You can even name it whatever you want – Apple is really letting you go nuts here.
Of course, there are older elements from previous iPhones on offer as well swiping left to access Spotlight search for instance.
This offers the chance to simply type in a search term, and Spotlight will search out messages, applications, contacts or media files containing that name.
If it can't find them then it will offer the chance to hit up the likes of Google or Wikipedia to get more information – but you can probably work out how to do that yourself.
It's not the most intuitive search – other platforms will let you perform functions like sending a message reply from the search results, but it's still jolly handy for things like finding a certain song.
Voice control is also on offer too – hold down the home button and a little blue screen pops up.
The idea is saying things like 'Play Album Immersion' or 'Dial Marc's Mum' will do such a thing – in reality, it was useless.
We swear it's worse at working out what we're trying to say than the iPhone 3GS – so many times it decided to dial a random number instead of playing a song.
But the schizophrenic robot voice control aside, iPhone 4 interface is simply immense – from the super-smooth and responsive swiping to the instant opening of applications and animations, the reasons so many people like the iPhone is evident under the touch.
It doesn't have the instant zip of the Desire or Samsung Galaxy S, but that's more to do with the animated transitions than any kind of judder.
We're still gutted that elements like widgets aren't present – you don't hang a picture of a fridge in your kitchen to keep your milk cold, so why should you have to open an icon to access information from an application?