When speaking of the iPhone and the iPad, Apple SVP of design — and again, how many hardware/software companies have an executive level designer? — said he did everything possible to get the device itself out of the user’s way. It’s just a screen. Apple’s software designers have done a little of the same. But maintaining consistency to such a a consistent degree, a significant part of the OS gets out of the user’s way as well and only the content is left.
Just for fun I passed around a few non-iPhone devices to co-workers, all smart techies. It took them a while to do even basic things like turn them on, unlock them, find Wi-Fi and add the password…
In stark contrast I’ve mention numerous time how I’ve given iPhones, iPod touches, and iPads to children as young as one and half and they’ve been able to unlock them and launch the apps they wanted to launch. At two and half they could use it well.
My own two and a half year old is adept at using the iPhone and the iPad, two devices in completely different classes. She knows how to power them on, unlock the screen, and find the app she wants. She's been using the iPhone since she was seven months old. By the time she stopped chewing on it and understood that it's not a teether, she began looking for games to play on it. After understanding how iOS 3 works, it took her seconds to figure out that I had hidden all her games in a specific folder once she got her hands on the iPhone 4.
Her favorite apps are Angry Birds, AniMatch, Let's Golf (she can't play it but is fascinated at the intro video), Flight Control, Creamy Ice, Harbor Master, Sky Babes, and the Toy Story book iPad app. Aside from Let's Golf, she's quick to figure out how to play those games.
Thanks to the consistency and simplicity of the iOS interface, there's very little learning curve beyond reading ability and motor skills. Apple has done very well to get the device out of the way and get the user to start using apps.