One of the first things that usually hits a person traveling to a new country is bewilderment. Incomprehensible cues abound in the form of unreadable signs, unfamiliar cultural norms, and seemingly chaotic behavior. One of the most striking examples of that is the foreign supermarket - what at home is usually a shining example of order and predictability [at least after your first few trips], is abroad one of the most confusing places. Which is why people find the app-centric design of the iPhone so comforting to use.
That is to say, people tend to appreciate clear signals and reliable mental models as they go about trying to live their lives*. In your local supermarket, not only do you have a solid spatial representation of the entire place, with little mental flags for the important aisles and possibly a script to follow as you go about your grocery shopping, but there are also very clear signs and well-known implicit categories [vegetables tend to be near fruit in the produce area]. Human beings thrive on sorting things into clear categories, scripts, and schema so they know how to operate. In a foreign environment the products are different, the layout different, the categories often unclear, and your scripts don’t apply.
So what does that have to do with the iPhone? As Nokia’s head of design [Marko Ahtisaari] has noted, there are lots of possible ways to interact with a smartphone. The whole app/widget model is not necessarily the only or “best” design in the world [i.e. one quick alternative: having the home screen dominated not by apps to select but by content or notifications].
But what’s nice about this dynamic is that even though there may be a potentially overwhelming number of apps on your phone, each app very clearly does one thing. When you’re using that app it occupies the majority of the screen, immersing you in the task. You know exactly where to find weather info, which app to use to find a local restaurant, how to access your internet radio stations. Each app carves out a discrete task area and communicates that to the user. Even the marketing goes along with the idea of clarity, simplicity, and task efficiency [“there’s an app for that”]. In general, one need, one task, one app. It’s straightforward.
The end result is that it’s remarkably easy to intuit the workings of the iPhone interface and app model, even though it ought to be complicated. The scripts are simple, the categories are clearly defined, and the spatial model fits easily into our brains. Moral of the story: create clear expectations, category boundaries, and mental mappings for your user. Make their experience the exact opposite of trying to buy cereal in China.
*except for some people in some circumstances where figuring things out is an enjoyable challenge - i.e. travel, exploration, games, etc.