Apple has showed off iOS 6, which will be coming to iOS device this fall. Apple fanboys will be eagerly waiting for Apple's new mobile operating system, but not all of the key feature will work on all Apple devices.

The official iOS 6 Preview page is already up on Apple's Web Site. As the tech giant calls it, iOS 6 brings more than 200 new features and updates. The most significant of these are FaceTime over 3G, Siri for new iPad, Passport, new Apple Maps app with turn-by-turn navigation and real-time traffic information, Facebook integration and shared photo streams. But, it looks like that Apple iPhone 4S is the only current iOS device to get all these features.

The age-old iPhone 3G and original iPhone will not be getting iOS 6, just like they were put off from iOS 5 update list. Unfortunately, Apple has removed the original iPad from its iOS 6 update list. It looks that the original iPad will not be getting any future updates too.

iPhone 4

Apple iPhone 4 is undoubtedly getting iOS 6, but it will miss many key features. The new Apple Maps turn-by-turn navigation and flyover mode (earlier known as 3D Mode) won't work on iPhone 4. FaceTime over cellular network is also missing.

iPhone 3GS

Like iPhone 4, users will miss 3G FaceTime, turn-by-turn navigation and flyover mode in iPhone 3GS. It also misses VIP mail and shared photo streams. Moreover, the offline reading lists mode will not work in Safari. Apple iPhone 3GS owner still need third party apps like Instapaper to do that.

iPad 2

Apple iPad 2 is getting most of the feature of iOS 6, but it will still miss a few of them. FaceTime over 3G is not operational in the second generation iPad. Passbook app is also not available for the tablet. And iPad 2 seems to be the only dual-core powered iGadget that is not friendly with the voice assistant Siri.