The wait is almost over and iO7, the first version of the iPhone, iPad and iPod Touch operating system designed by Jony Ive, the brains behind the physical look and feel of all Apple devices, will be ready for download on Wednesday.

However, there's a catch. Even if your device is compatible, not all of its promised 200 new features will be available to everyone.

Just the quickest of glances at the images and videos showcasing iOS7 will give non-believers some idea why the Apple community is getting so excited about the upcoming software update.

As well as a totally new look and feel, the latest OS also brings a raft of new and innovative features, including a serious overhaul of Siri, Apple's virtual assistant to bring her performance more in line with what arch competitor Android offers via Google Now.

So, when asking Siri for help she can plug directly into Wikipedia, Twitter, Bing and the user's photo album or, in the case of stressed-out commutes, transit routes, and new updates to make sure they're on time for work and avoid the jams.

But not all of the headline features will function on every Apple device because of processor, RAM and screen resolution requirements, so here's a breakdown of what iOS7 will do on different devices.

AirDrop
A system familiar with Mac desktop owners, AirDrop is a protocol for sharing files over wifi, even when there is no wifi signal (it turns the devices into a hotspot) and it will be coming to the iPhone 5, iPod Touch (fifth generation), iPad 4 and iPad Mini, but not the iPhone 4 or 4s.

Updated Siri
The virtual assistant gets a new graphical interface, a selection of male and female voices, and the ability to tap into Bing and Wikipedia to perform web searches. He or she will work on the iPhone 4s and 5, the iPad Mini and on any full-sized iPad with a retina display.

Camera enhancements
iOS7 adds lens filters (which will only be available on the iPhone 5 and iPod Touch fifth generation) for applying effects to the scene or object before taking the photo, plus image filters -- which will be available across the iPhone 4, 4s and 5 plus iPad 2, 3 and 4 -- for adding effects after the picture has been taken.

iTunes Radio
The free internet music service, which allows users to listen to ad-supported stations will work across all iPhones 4, 4s and 5, plus the iPad 2, 3 and 4 as well as the iPad Mini. Subscribers to Apple's iTunes Match cloud music storage and streaming service will be able to tune in ad-free. However, to begin with at least, iTunes Radio will only be available to US consumers. Apple has set no date yet as to when it is expected to go live in other territories.

Other features
Any updates the iOS7 brings that are to its pre-installed undeletable apps, such as the calendar, weather, stocks, note-taking, web browser, email and of course, Apple Maps, will work across all compatible devices.